Hmmm, only these come to mind and they are the only stuff on my mind now as I play WoW, waiting for the expansion:
- No update to the Classes VFX even with the new Hero Talents. (God, DK needs it soo bad IMO… compare to other CLasses!)
- No Chromatus or Twilight Dragonflight
- No real ending, after the end of World Saga. (Finished it with another looming thread instead of start to develop a new story forwards)
- Horde Villain batting yet again after teasing Alliance inner corruption (if it even exist within its faceless and nameless nobility).
- No DH 3rd spec and 3rd Hero Spec or other at least elven races. No Meta customization. No flying as a DH Class?..this is long over do and the lore supports it even before Drakthyr a created to have this racial. Vengeance Meta should even have his fiery wings in when gliding, I seen the assets for it… why it’s not added yet?
- No new lore or new Assets created that would benefit the Players Gameplay and Avatar - Racial and Player Preference Identity (Religion or Racials VFX for certain wielders of Orders of the Light or Shadow Cult associated Classes like Priest, Shaman, Paladin etc)
- No option to be a Human or Nightelves Worgen… I like to see other races too if possible but Nightelves are long over do to be an Option.
- No Evokers Visages for other races… OH almost forgot!! THINKER BIGGER more Draconic looking Drakthyr… they skinny lizard look is fine but I like to look a bit more like Drakonids if possible, maybe adding a body option num. 3?
- No expanded Runeforging for DK, maybe add Necromacy, Fleshcrafting and Rune Carving you know like a minor version to access to Death Theme engineering, Augmentation or Healing (Runeforging update should have happend in SL or after it… WE HAVE UNLIMITED ACCESS it the FREAKIN SL and its main Covenant Leaders for God sakes, its literally the source of a DK’s Power we even have Fire in the Maw and DK are not even accessing this!? And DK are STILL using the same VFX and runeforging since what? Legion… COME ON, lore wise it makes no sense DK updates have been so minor, even visually IMO!)
- NO expand to the Forsaken body options, like again they have access to the Shadowlands… why are they still walking zombies when they can now fleshcraft themselves new bodies?
Give them Darkfallen skin for humans, add skeleton, lich, Ghost form or Slime skeletons forms to them… Use Kutirian Skeleton to give em access to Abomination look! C’mon the lore is open the pandora box WHY the Forsaken and DK can’t be updated with more Body Option?!
I know it takes A LOT of dev time to even make some of these PC playable… but if anyone could pull it off its Blizz… (IMO)
That’s all I got for now… 
This is my last edit I swear! 