They were stated to be updated as well. Blizzard said they would update everything except Cata races and onwards, but they would work on the older races first. So, yes, Draenei and Blood Elves are getting updated.
As far as those troll skins...they're just skins. I agree that Vol'jin and Mar'li look awesome. Hell, the entire Zandalari Council in ToT was consisted of four different troll skeletons with new skins slapped on them, and they all looked great...except they still had horrible animations. They moved very stiffly compared to Pandaren, or even Worgen and Goblins, because they only had new skins, and a couple had new animations (like Kazra'jin's roll). I'm much more excited about having smoother movements on my characters, on top of having more detailed features. I especially would like it if my Night Elves could have moving hair that doesn't look glued on, or a Dwarf that doesn't have his beard glued to his pubes.