Eh? That will never happen, never.
It's not only WoW's style, it's Blizzard's style, Diablo is a bit more realistic because of the tone of the game, but it's still using a similar palette and hand painted textures and so on.
A lot fits in each game, compare Diablo's Mystic, Jeweler and Blacksmith stations to the profession buildings for Garrisons for example.
Theres clearly a huge detail and fidelity upgrade in WoD, even over MoP.
As for Trees, well, they've never got them right, it's kinda hilarious if you go back to Quel'Danas now and look at the trees, which looked pretty amazing for TBC trees tbh.
I think the tusks are unfinished though, they clearly look out of place in regards to quality in comparison to the rest of the body, at least on that screenshot, but it may just be from artifacts and compression.