The current approach just seems the worst of both worlds. We get these goofy-looking lizard-people, who aren't even a REAL race (almost zero transmog options), have NO passing connection in the game's lore, and apparently they fucking STILL have to go into Visage form to use mounts.
With so many restrictions in place, why not just make them LOOK like proper dragons -- just scaled-down to be comparable size to Druid forms, or Worgen's Running Wild?
For one, you don't then need to create a bunch of bullshit lore about WHY these humanoid-dragon-abominations exist, you can simply say "hey, Deathwing experimented with creating a "Prismatic Dragonflight", they're relatively young or just very small compared to other dragons". Boom, all bases covered.
And since the whole thing about the Evoker is that it's SUPPOSED to be a "playable dragon" class, well, wouldn't it be a whole lot cooler if they actually LOOKED the part? Instead of just looking like argonians from Elder Scrolls?
I would think making this shift would be a total slam-dunk for Blizzard. They still get to avoid adding all of the "usual" shit that genuinely new races need (custom-fit armor and transmogs, all sorts of animations, obvious clipping issues abound), and as a FANTASY, there's no denying that being able to "play as a dragon" -- again, even if physically smaller -- would be pretty freaking sick.
And personally? I'd let players choose any race (or at least those native to Azeroth) to use as a "Visage" form. Even if they don't get the "Dracthyr customization options", I personally think they kind of look like shit anyways. The horns are kind of cool, but I'd happily sacrifice them to not be stuck as a human or blood elf (nothing against those two options, but I think a Dark Iron or a Nightborne might better suit the sort of "look" I would gravitate towards).
Also... If you make them ACTUAL, smaller dragons, you can literally just call them "Dragons". I think that sounds way, way, WAY cooler than "Dracthyr". I'm also not particularly keen on "Evoker" (I initially thought it was Invoker, which I thought sounded cooler), but that's whatever.