The devs would rather give something fun to do to the players than something that might be repetitive, not as attractive, or even problematic in the long run (as it happened with attunements in the old days).
That's something that Mists of Pandaria will try to improve through various means both when players get to the cap level and on their way there:
-Daily quests (there's roughly, around 300 daily quests in Mists of Pandaria. Although these are randomized, you'd have around 48 quests available on any given day, and you can do as many of them as you wish).
-Challenge modes (which might be especially appealing to the more hardcore crowd)
-LFR & 10/25 man normal/Heroic raids.
How exactly are Dailies and multiple versions of the exact same Instance not repetitive?
In fact, their whole purpose (now) IS to be used as repetitive content, content you'll be doing time and time and again to collect some bogus points that most of the time the next Patch will make 100% worthless.
Sorry, but saying that having to finish a Questline just ONCE per character (attunements, Keys) is more repetitive than the gated abomination of Dailies and the point-grindhamsterwheel of doing the same 'Heroic' Instances time and time again over the whole of an Expansion is rather incredidulous.
And of course: perhaps it's for players to decide what they think is fun content?
Look, I undnerstand the issues with the Raid content: it makes no sense to keep sacrificing so much of the game for it (levelling has been ruined because of it for example), and so to justify it a bit, as many people as possible must be rushed to max level to sit in a queue and (hopefully) 'Raid' , and so Raids must be made as accesible as possible.
Which means attunements etc. got the axe.
But the real lesson of those 'only 1% saw naxxramas' figures is that perhaps it makes much more sense to stop concentrating so redciulously much effort on Raiding, and more on the other apsects the game used to have.
If the vast majority of the player base does not Raid
(e.g. http://thegrumpyelf.blogspot.nl/2012/06/is-raid-content-really-compelling.html but there are plenty of other sources)
and in fact the vast majority of the subscribers doesn't even have a single character camping the last bracket
( http://childrenofwrath.blogspot.co.uk/2012/02/numbers-20-insight-into-design-theory.html , same) ,
it becomes pretty clear that instead of GC c.s. forcing others to have the same interests, the devs should satrt spending more attention to other parts of the game - and/or to hire new people that can develop such content well
Given the popularity of PvP content
(check Blizzard's own Poll http://eu.battle.net/wow/en/forum/topic/1679609273 ; over 70% of the respondents liked one or more types of PvP, the option 'I don't like PvP' was included)
doing a much, MUCH better job with the PvP content and balance (ie the stupid WSG GY change, Heirloom-caused Gear imbalances in regular Battlegrounds etc.) would be far more logical, for example.