MAYBE they looked that way because, you know...they didn't have anything more to work with? You'll also notice how the pre-TBC character models were absolutely void of emotion apart from a few pasted face options with a permanent snarl or smile or whatever.
Now they have brought forth what they envisioned, and sorry to all the people afraid of "childish things" but still playing a 12+ game KNOWN for its cartoony style and for not taking itself too seriously, but you can always use the old models I suppose.
I love how the new models can display anything from goofiness to serious bloodthirst.