WoW is an illusion, so is MoP and so is the entire reality that lay before your eyes.
The entire universe is nothing more than individual particles En-masse reacting (or not reacting) with one another in a manner described by quantum physics.
So yes, in that sense, MoP and thus the changes therein are nothing but an illusion.
What exactly should Blizzard change in MoP? Should they add various alien races, and space ships? and light sabers?
WoW is WoW, SWTOR is SWTOR, Final Fantasy 11 is Final Fantasy 11, GW2 is GW2, and they will each follow their own path which will never stray radically. If you want to play a game that is fundamentally different and nothing like WoW, then play a game other than WoW.
Okay, this EVERYTHING was missleading. But what did other expacs bring about class/mechanics change?
1) BC - big fix after vanilla. Bear druids started feeling useful, retri pallys as well. Warriors were encouraged to dps. But about the mechanics themselves? No real changes. Same talent tree structures, rotations and stuff
2) Wrath - "noob support" era begins: players are awarded for being lazy and sucking at playing. Talent trees are copy-paste from internet. Introduction of DKs kinda messed things up - they were either too op or too lame, no one knows. Glyphs were added - also copy-paste system, no one cares.
3) Cata - let's try to make changes. Reforging as a system to make players understand their priorities, "boring talents" removed, more glyphs, changes in rotations and mechanics - and things remained the same. Talents and glyphs are copied, reforging is at best about reaching caps (mostly like reforge everything to X). After first try of making content difficult and massive whine "AMG cant do a hc mobs hit hard wat is cc" made Blizzard give up.
4) MoP - TOTAL revamp of talent trees. Now you have to make important choices - and at least 2 choices that really change playstyle in a tree. If they gonna scale properly you wont be able to just copy builds, as one would fit on this fight, one for that. Lots of new glyphs, and getting rid of "+5% crit change" glyphs. Classes like warlocks get a TOTAL revamp. Rest is forced to think how they play.
You are being quite negative here in my opinion, OP.