TL;DR included.
I believe the highest tenet of any RPG to be the players’ ability to identify themselves in their character. An expansive and thorough character customization system is usually encoded into RPGs to allow a player total control over the appearance and style of their characters, allowing them to immerse themselves into their adventures.
It’s no secret that Warcraft’s ability to customize our characters in comparison to other MMOs and RPGs is limited, an unfortunate consequence of our aged game engine. Despite Blizzard’s efforts to remedy technical limitations as best they can, some exceptionally popular requests (sliders, height, weight, etc.) have little to no chance of occurring because of the core structure of the game world and its engine.
These customizations may be a standard baseline in more recently released titles, but I understand and accept why we can’t have them here. It’s just not feasible without a complete rework of what makes Azeroth, Azeroth.
That said, there is still so very much Blizzard has not yet done to expand our customization in other ways. The recent, and rather unexpected, announcement that we will soon be able to hide all armor besides our legs is an incredibly welcome change, and a very positive one. But we cannot stop there. Thori’dal still gathers dust in my bank, forever unused and inaccessible. Thunderfury gathers dust in many other banks, again unusable - despite Outlaw rogues having a hi-res, modernized version of the model.
Many of our player races have extremely limited artwork to choose from; tauren females have 4 faces that are all virtually the same, human females have 15 faces, but the most striking differences between them are the shades of makeup applied. Void elves have 6 skin tones, 4 of which are almost completely identical, and there are so many more examples to draw from.
TL;DR:
Again, I understand the limitations of the engine, but these limitations can be made up for in other ways. Allow us to transmog legendaries. Offer more unique faces and skin tone options for all races. Touch up Nightborne - particularly males - and Lightforged, and give them both more than 3 skin tones to choose from.
We have 21 playable races now, but every one of these 21 races has far too few options to choose from. For the health of Warcraft as an RPG, we need more.