The absolute best part about WOD thus far has been no flying and selfies, the absolute worst is arguably the lack of major cities that are some how connected to the story (this part played by the second worst thing to happen to WoW, garrisons). I would like to see this change made to the entirety of the game, and if flying was brought back in anyway, it should be put on a fatigue bar that forced you to land intermittently to prevent suspended flight.
The game is becoming MOAR cartoony, instead of the maintaining the dark undertones of places like Deadwind Pass, Kharazan, Stratholm, Undercity, anything to do with wrath was pretty dark (but could definitely be darker), etc... and I HATE that. Diablo to some extent doesnt even take the darkness far enough.... and its totally doable in wow to make things dark and creepy instead of light hearted and weak.
Slut armor is great, but the early versions of it are poorly designed. Not to say stuff like the armor in tera is anything that should be used as a guide (it fucking shouldnt) but we could do with some more skin and creatively great armor.
There is too much unused space and your FUCKING CRAZY if you think that questing and leveling in wow is the least broke part of the game (:
For every spec that exists, there should be talents that allow you to TRULY tailor your spec to different factions. You should totally be allowed to switch between specs available to your class, without discrimination. There should be subspecs (3 per tree) that are completely different from eachother.
WoW needs to make greater use of its worldly resources including the addition of factions around azeroth's unused zone that unlock everything from mounts, cosmetic transmogs, class rewards and modifications to cosmetic model effects and toys.
Dungeons should have more bosses, and there should be a mythic tier of seperate dungeons that do not use LFD and have server lock outs that return equivalent quality gear to the current raid tier, recoloring armor here is permitted. This could even be a prereq to your raid team's unlocking the door of certain bosses in tier raids (similar to kharazan is what i hear this is, but not sure cause i came in around wrath).
Theres absolutely no reason for the long ass cooldowns on cosmetic shapeshifting toys... especially for so short a duration. If I want to walk around looking like a god damn furbolog, i have every right to. Neural silencer should work if you have it in your bags, have no internal cd, and be infinitely tradeable among players, damaging trolls for years.
Transmog tab... i dont know how i feel about this... but I like that my bag space makes me prioritize what I do and dont carry in my bank... though I wish I could use my bank for other things like all the freaking consumables I have. I like the enforced choice when it comes to the bank, and Im not fond of them changing the current tmogg system except of course taking the idea a step further and actually having the icon, name, and model of the old gear while having the stats of the tmogged over armor.
Set bonus changes should not drastically affect gameplay. These should be cosmetic changes at best. Reason? If you have to make a set bonus for things, then it should just be part of the class. See all the baked in changes from the 5.4 sets into the 6.0 classes.
Game changing talents like glad stance for warr and COM for spriests should not be left to the end. Having them earlier would be much more benficial to leveling and at the point you reach cap with them... its kind of just this thing you have that you WISH you had many many many moons ago instead. <this is for the altoholic in me, as most people sit at cap and are unaffected by this change>.
Blizzard's story lines are not bad, but lack depth. NEED MORE DEPTH, and darkness.... I mean its the world of warcraft... and there are days where I feel like its the world of beautycraft instead. Sure the world shouldnt be 100% dark and gruesome, there should be places that contrast the dark which will bring more beauty to the beautiful and more dark to the dark. Theres no contrast in WoD (even the arrakoa and shadowmoon areas are pretty, even if it is night). Damnit... I made a circle....
MOAR DUNGEONS, LESS LFD! I advocate calling this mythic dungeons, should be 1 for every 3 lfd dungeons and should be unique, server bound, and 4 for every expansion start and another 2-3 by the end of the expansion. 6-12bosses.
STOP REWORKING MY FUCKING DUNGEONS. If you want to do something, update the graphics ONLY. Dont fuck with what was there. Its not likely you will do something good to them, maybe make the bosses and trash hit harder... but again... dont fuck with them. the style, the mechanics, etc... just dont.
Those are all I care to think of atm. Will post more if anyone reminds me of any good ones. Sorry for the rambling. I feel like I should be employed at this point.