I wanted to point one specific problem which started since the change in game systems designers in late TBC (aka coming of GC and his team, introduction of tight enrage timers and other bullsh!t, sorry). This is so called "flexible raid roster" problem. One fight requires x1 tanks, y1 healers, z1 dps. Other fight requires x2 tanks, y2 healers, z3 dps. Admittedly, in early TBC there were situations where it would be faster to do things for different fights with different amount of roles, but it was never requirement. For as long as you had roles covered, you had your boss kills unless your raid was performing really awful and consisted of green-geared people. If some fight could be done with 1-2 less healers, you could have those 1-2 for insurance.
This thread explains this problem very well in all details (though it was written yet in Cataclysm, problem still remains):
Together with this problem, we have another problem - global class exclusion. As you could see from class representation in raid with full Heart of Fear heroic clear (which was published earlier on this site), they had 0 rogues in their 25-men setup (post Garalon "fix"), which we know wasn't due to lack of rogues in their roster, but because rogues have no place in MoP raids (I am so glad I don't play rogue), especially after Garalon "fix".
So how do people look at this current raid design approach? If this expansion was supposed to be more TBC-like (pre-SWP or rather pre-Ghostcrawler), why does it fail in almost all aspects?