Keep alter, but don't let it reset icicles/brainfreeze procs. Also, make it so pom can't be altered.
Alter time is a really cool spell that has counter play and both defensive/offensive utility. Just nerf the offensive utility of the spell.
-Primary focus should be made on make the game fun, not balanced. Wow is not going to be an e-sport so it might as well be fun. Trying to make the game balanced has really bloated the amount of abilities in the game, making is very frustrating to play for everyone. Things like melee have to sit through 20 roots because almost all caster have them, shadowpriests trying to cast when all melee have 3-4 ways of stopping you from casting.
-Make it so pvp gear is still superior in World pvp enviroments. Can't get a healer below 90% on timeless isle.
-Take away flying mounts from old zones, new zones should just be ground mounts but this is probably not a popular opinion.
-take away lfr and make lfg just fine the group but you still have to get to the dungeon instead of teleporting there.
-Make the next expansion something a little bit more "dangerous". Meaning this panda shit is dumb.
-I know it fits into the lore, but create another neutral city with a dueling area.
-Have no idea why they tried to change the dispel system from wrath. It was already really engaging between trying to set up situations where the healer couldnt afford to dispel ua, or where it wouldn't be worth the rng to dispel your warrior's nova with 4 stacks of icelance because your other partner is taking damage. Idk, I guess i just thought every healer having their own unique roll to fill was really cool. I liked that rets, although they weren't top tier, had defensive dispel and that made them unique and gave some people a reason to bring them or play them. Instead of where they are now which either a worse dk/warrior. That goes for most hybrids. Moonkins brough the utility of cyclone, and though they weren't strong, it was reason enough for some people to play them. I always enjoyed playing unique or obscure comps/specs where I could say that I was actually playing a moonkin instead of a worse spriest or a worse warlock.
Most of these ideas are really far-fetched, but I think they would create the illusion of actually playing in a fantasy world. I think the lack of world pvp and some sort of importance of significance of your character actually being something you have worked on. As cheesy as it sounds, you should be able to feel some sort of pride in how hard you have worked to make your character "strong".
edit: I forgot to say that I think pve gear in arena isn't always a bad thing. If you want a small advantage because a trinket or weapon is slightly better than the pvp counterpart it's fine. Makes the game more well rounded without making it manditory.
If you are human or undead you don;t have to use pvp trinket. As a troll, I switch between both on use and pvp trinket depending on comp. I have been running a lot of warrior mage and rogue mage so I like my enchanting/enchanting. The back proc makes for mondo butthurting icelances that force all cd's in the opener.
I hope I was helpful, and good luck in icelancing nerds hard.