Story development/progression - I’m alright with where we’re going so far.
Temporary systems/borrowed power - The idea of these temporary systems with borrowed powers gone. At least the level of focus these systems have seen since the start of Legion.
Classes and specs - brought back as the major focus of, and basis for, combat and expansion-specific features. They should feel like, and function as, complete entities without needing expansion-related bonuses and abilities.
Identities/fantasy - Classes and specs can retain their modern focus on added depth and identities for each individual spec(with things like spec-specific talents).
The old Survival-spec hunters used to have prior to Legion - A modern version focusing on the DoT-concept and the theme of a Munitions Expert and Trapper, as a 4th spec option. A version with the same depth and involvement as can be seen with all other specs post-WoD.
Link: [Updated for Dragonflight] Munitions - If RSV was to return
Glyphs - A way to further build upon and add more depth to classes/specs, I want the old Glyph-system brought back with effects that have an impact on gameplay, not just cosmetics. Add in enhancements for most of the core elements of each spec as well as class-wide abilities. Allow players to customize their character based on whatever they want to do themselves, such as PvE; M+/Raids, PvP; Arena/BGs, or various open world content; leveling/soloing/questing/etc.
No more mandatory requirements - to push through which aren’t directly tied to the specific content you want to do, just so that you can get into said content. Example: Soul Ash(Cinders)-grind in Torghast for Legendary powers which are more or less required to do for example high-end raiding etc. Example 2: Island grinding for Azerite-power just so you’d be able to benefit from mythic level pieces of Azerite-gear if you managed to kill bosses that dropped them early on in a tier. I killed the boss, I got the item, I should be able to use it right away. If you want players to engage in content, design the content so that the players actually want to engage in it. Don’t design it to a point where players feel forced to do so, just so that they can use it as a means for something else which is what they really want to do.
More options to do dungeons/content - that aren’t tied to “speed-running”. Keep it for those that want to, but add ways to do them without that as a focus for progression. Stop putting a forced timer on things.
Flying-capabilities - stop delaying that until later patches via timegating. Make players level up their character(s) and explore new areas, and that should be it in order for us to be able to unlock flying in new expansions.
Bonus - Double down on the “New Player-experience”. For teaching purposes, add in tutorial quests designed to introduce you to new abilities as you level a new character/class up. They don’t have to be mandatory ofc. And they should only focus on Core Abilities for specific specs, and perhaps certain key-utility and class-wide abilities for entire classes. This exists for the beginner-stage on the newly added island for sub-level 10 characters, but as far as I know, it does not include anything tied to specific specializations which are chosen after.