1. They attempted at making CC a thing again in Cata and what tended to happen most of the time is people would run full force into a wall, or even better break CCs because all we knew was kill all the things.
2. I'm fine with the old talent system being gone. I don't mind the current talents and I always felt the old ones were incredibly bloated. I would though like to see more options for tiers, instead of three.
3. Again, if I'm not mistaken they attempted to do this back in Cata and I recall being on my protection warrior and having a hard as hell time to actually hold agro, mainly because people always tend to go balls to the wall on anything.
4. There's only so much you can do in an MMO to keep things feeling different. Class wise it tends to be looks and abilities. Have to remember WoW keeps the "holy trinity" of tank, healer, damage. Casters are casters, tanks are tanks, healers are healers. Nearly all of the classes play similar. For instance rogue and enhancement shaman. They sit in melee and hit things, just they do it differently with different things. This can be said though with nearly any video game though.
To me dungeons should be fun and some what challenging. I think they got it right with MoP with how dungeons feel. Normal dungeons were semi difficult going in when you're a fresh 90, and heroics were a challenge if you ignored mechanics. Obviously now with it being the end of the expansion and people out gear the dungeons people burn through it, which is fine. Do have to remember we do have challenge modes if you're looking for something challenging.