If it is redundant to have a 3D model of your character, then wouldn't it also be redundant to have a hand-drawn picture of your character? I feel that if you forget what class you're playing, the resource globe may give you a hint. ;)
I dunno. Just feels like wasted space and talent when I've seen what this team can do. The inventory art, the art deco designs, the directional patterns from the BlizzCast 8 UI were really stellar, too. I have no problem with simplicity, but I don't think it lives up to its potential in terms of ornateness.
The main difference between the two is that the recent paperdoll shows you where your item belong on your character; so it's easy to spot the leg slot, the head slot etc. Where as the 3d model would take the center, and the items would be set in a circle around it - it wouldn't be as clear where the head pants, gloves are.
The 2d drawing of the character is more filler, I don't care so much about it, but it doesn't bother me too much as it is. I like that everything is easily accessible though, it's better than if the talisman was hidden in another tab. It might create annoying bag issues like the Horadric cube does.