I don't see a real problem with it other than the utility part. The longer the game goes the less there is that defines classes. Its one of the more disappointing things thats gone on since the whole " bring the player " thing. I rolled a Paladin because I wanted to be a support class, oddly one of the reason I chose Ele in this expansion is that it still had much of that feeling.
Current fights are not interesting though. The vast majority of them just spam aoe crap on the ground forcing you to run around as a headless chicken to avoid it while spamming your main move.
I'm happy with caster mobility getting nerfed maybe now melee will finally stop being overlooked.
Yep, and they had to nerf encounters like Siegecrafter where you do need the utility because 10s couldn't always bring it, which is why the move to 20 Mythic. Taking the tools away (which includes longer cooldowns/more shared DR) from those who do have them is going to leave 20 man raids just as likely to be short, with the same consequences.
I personally think it might get even harder. With the removal of lots of instant cast and "cast while running" taking away (except from hunters), it will sure put pressure on DMG done and healers.
But only time will tell if the new raid encounters are harder or not (only counting Mythic difficulty thou).
Restricted movement is quite fun due to the fact that they have to tune the players capability while standing still, which means that a couple of fights will be about how you can reduce the movement to the minimum, which can be fun for the guild with making up tactics (can be boring if it is too much of the same kind though.
Also for the individual player requires more skill than just pushing buttons.
When a player has to make decisions based on their mobility (or lack thereof) it makes for more interesting encounters, IMO. It also separates the smart players from the less smart players.
Making the decision between moving or finishing a cast can challenge both your survival instincts and your performance.
Moving 100% of the time without penalty takes away a large portion of decision making on a player's part effectively making an encounter less interesting.
Just my two cents.
Don't need more utility with 20 man raids. Adding more shit on top of what we have now will just significantly lower the skill cap of raids etc. They have to balance everything again with the new raid size. Don't worry there will always be gimmicks that will force bringing a particular class to raid so they can shine.
Not sure how having tools and being made to use them lowers the skillcap compared to the alternative of not having them, and so not being asked to do any more than your DPS rotation because of they're not there.
Updated the OP to be a bit clearer on what utility actually is, and what the scaling back of it actually means.