The nature of MMO game design requires pacing mechanisms that can provide interest to a pretty wide array of players for a long period of time that are also robust enough to allow those that play occasionally to not be left in the dust by those that poopsock. The main pacing mechanism that WoW embraced early was obfuscation - you didn't know exactly where the quest objects were, where the guy you had to find was, what abilities the bosses had, where ideal loot is, what the mathematically best spec was, etc.

You had to figure out the world, explore, find quest givers, learn your class, determine your best gear, figure out bosses, and so on, and the only real tools you had were in-game social groups. This was before forums were a big thing, before even Thottbot. And in turn, it was the ignorance of the players - the obfuscation of the mechanics - that created a significant amount of gameplay. But the increased social aspects of the internet led to the elimination of these obfuscation mechanics. People exploring and discovering new and interesting things have a very different sense of hurdles than people who have a very clear goal and want to knock it out before moving on. Hitting 60, sitting around and trying to get into any new 60 dungeon just to see what's in it has a level of excitement and tension that is only heightened by having to hunt for a group of people to run it with. Having been 60 a long time, knowing exactly what you need to do and what boss drops the loot you want, sitting around trying to find people when your usuals are busy is just a PITA.

And that's the real distinction. People generally figured things out. They were able to look for gear with good stats for them on Thottbot, discuss builds on forums, got together to work on the math for the skills. I wrote up a guide on gearing for/running MC for the new hunters to the guild, teaching them in a few minutes of reading what I had to learn over weeks of experimentation (for example, the rogues did not think 'attack power' also increased 'ranged attack power' and the only way to show that it did was to get a bunch of attack power gear and run tests). On the one hand the guide was great for our guild, but on the other hand it eliminated those weeks of content for multiple hunters. They wouldn't need to find and gather a pile of attack power gear, figure out ideal mobs to test it on with a static amount of armor, normalize for crits, etc. They could just ask and get an answer. Or take the quest in Dustwallow Marsh, where there was a burned down inn and you were asked to investigate. You had to actually look carefully for oddities to find all three objects to inspect to continue the quest chain. That could take a solid 20 minutes of looking. Once that information made it to Thottbot, you could do it in 2 minutes. Click this object, it is right here, here is a picture with the object circled. The need to figure it out on your own gave way to the need to figure it out from in-game social groups to the need to simply google it and look it up on a community site.

And ultimately lots of the obfuscation that added content was viewed not as a positive but as a negative. Quality of life improvements, from sparkly quest objects to more direct quest directions to added graveyards to summoning stones all improved your game by letting you get right to what you wanted to do (kill things, take their stuff, click the sparklies) but also eliminated all the content that came from having to run back after dying or sit in Org /1 lfg any 60 instance or wasting time trying to figure out what things did or where to go. That's where things like cross realm battlegroups came into play - there were many servers where if you wanted to play battlegrounds, you'd possibly sit around for an hour before your queue popped. It doesn't matter how many friends you have on your server, it's not going to make the queues go faster. The addition of a much closer horde graveyard to BFD, for example, was a huge QOL improvement...but it also eliminated the banter from running back and the running jokes about groups that ended up spirit rezzing after 20 minutes because they couldn't find their way back.

Cross realm dungeons happened for much the same reason - once the better guilds stopped generally running dungeons, they became ghost towns (particularly noticeable in TBC when you needed to run normal dungeons but everyone was in heroics). But don't get it twisted - the demand for dungeons increased because of the dearth of content elsewhere. Players no longer needed to spend an hour trying to figure out a quest, spending a couple days on a zone exploring and experimenting. They just pounded the quests out in a matter of minutes, clearing the zone in 2-3 hours. And the balance of Time Out Exploring versus Time Doing Dungeons became heavily shifted towards the dungeon side of things - you didn't really have anything else to do BUT dungeon and quest before getting into raids (since Serious PvP at lower levels was pretty much a joke sans twinking). For a GREAT example of natural player motivations hurting their own content pacing, look at the arena gear fiasco in the first few seasons, before rating requirements. There were a huge amount of people who made arena teams (myself included) simply to pound out ten games, probably lose most of them, but didn't care because it got them really high quality weapons after a few weeks. That eliminated, say, grinding lower city rep for the epic caster mace reward at exalted. Those shortcuts eliminate programmed content. Put another way, the push towards cross-realm tech, dungeon finders, etc., were ways of increasing accessibility to the content that was previously only a fraction of what you did but became the primary goal at the expense of all other goals.

That's the key. The players boiled down the gameplay by understanding it. And when boiled down, there's much, much less content because of how much depends on ignorance. That's why constant distractions or change-ups 'need' to be added - sure, you knew you were going to get another hundred quests to go collect bear asses in the last expansion, but you also get pokemans. In the next expansion you're going to get another hundred quests to collect bear asses, but now you have pokemans AND interior decorating. These distractions are 'neccesary' because "collect 150 bear asses this expansion" plays towards the third pillar of WoW style MMO content - grinding. People see it, don't like it, and often outright dislike it if it's insultingly poorly hidden. Even the dumbest dumbs in the barrens could figure out that Zhevras have four hooves.

Don't think I'm talking solely about leveling content either, obfuscation extends to raids. If you join a guild, you are expected to have studied the content that the guild takes on. You should know the fight pretty well before walking into the room. You should have various addons that provide a plethora of information to make your experience as straightforward as possible - threat meters, dispel helpers, power auras, UI overhauls, etc. Rewind and Onyxia's most significant mechanic was managing threat in a world before reliable threat meters. That's not anything anymore; a raid that doesn't know how much threat the tank has to two significant figures is simply not playing right. Obfuscation is one of the easiest barriers to overcome, and is something players WANT to overcome, innately.

Fundamentally, there are three primary tools of content generation for a WoW style MMO - grinding, obfuscation, or distraction. And people are pretty much tired of that formula by this point; WoW can continue to succeed because it's very, very good at what it does on top of the advantages of the huge amount of content and history and pop culture that comes with WoW instead of, say, Rift. But the exhaustion of the design is why 'WoW killers' really haven't been able to even make it out the door: they stick to the same three tools. SWTOR is probably the best example of this; they failed to learn from many of the mistakes WoW learned from (much less the ones they didn't) and as a result felt extremely dated right out the door. It's not just them, most MMOs looking to compete with WoW have done little more than take the formula and add some kind of a twist.

To 'fix' WoW, they need to fundamentally shift the motivating factors, reward systems, and economy. EvE Online, while absolutely not for everyone, is a system that is fundamentally different at its core. That's the level of distinction from the current WoW system that needs to be achieved to really fix the problem, because the underlying game systems within WoW are severely outdated, naturally pushing players towards a few specific activities within the game. But more likely, WoW will continue doing what it's doing and being the best at it until something else comes along that is substantially different. EQ Next is the first thing that I've seen to have even some measure of promise (other than Pathfinder Online, which is heavily based on EvE's systems), but I'd levy that more towards the utter lack of game system information available than any real positive ideas they've had. A dependency on procedural content does not provide much longevity in an MMO world.

TL;DR: People playing the game want to play the game rather than sit around. The method of playing the game has become more and more narrowly defined as completing instanced content. Therefore, the game has shifted around to accommodate that demand or distract from it, rather than upset it by changing the motivating factors.

SS's content is pretty boring though, its just alt+S+space bar = afk

everything is just tank and spank

most techs in SS dont even scale correctly, and the only usable tech at this moment is t20+, so noone bothers with below t20 content

the last time i logged in consistently and gave SS a go, i changed by zerk aug setup to make it stronger. unfortunately this dropped its speed from 180 to 60, and now travelling anywhere without getting incredibly bored is practically impossible.