These models are fine for unique characters that you only meet occasionally. The only reason Blizzard's models don't get this much work is because Blizzard has limited resources and they don't want to hire more people. So they have to decide between giving a character a new model or designing a new monster they can use over and over again through re-texturing. They usually choose for the latter.
Though from time to time they feel a character truly needs a unique model... for example with Thrall or Varian. Heck, even Tyrande and Vol'jin got one eventually because they got more screentime. But would you argue that the Ner'zhul model is more complex than the new Vol'jin one? Because I think they're quite alike (except maybe the staff). Korialstrasz dragon is fine as well. Grom Hellscream probably has too many accessories, you're right about that.
Wonderful, as always. You never defraud anyone: practically absolute perfection.
Tip: All the heroes you've represented are important, but I also would like to see Gul'dan, I do not know if you have it on your to-do list or not... At the end of the day Gul'dan is the only hero of the old Horde (along with Grom) who redeemed himself and would fit perfectly in the current Horde (and who knows, maybe Gul'dan himself could return of the very same underworld: his legacy is still undiscovered in the Broken Islands and his skull is more than enough to resuscitate him through the more powerful necromancy).
Personal desire: Seeing the uncorrupted Neltharion and the splendor of Soridormi, I have thought of how interesting it would be to return to the past to prevent that Neltharion was corrupted, perhaps with the excuse that the complete power of the Five Dragonflights is going to be needed to fight the Burning Legion. It would be a real honor to avoid the cataclysm and return Azeroth to its original charm (so we could see mythical places that were destroyed by the cataclysm, as Zandalar, Northeron or the missing half of the peninsula of Gilneas).
The Grom was is the best one, absolutely amazing.
That is freaking epic! If you've yet to do so, you should do Broxigar the Red