Well, it looks like I'm the only one, but I don't think cosmetic gear is a good idea.
I talked a bit about this in 2007. Your character model is on screen for 99% of the time. It's the one constant in your WoW experience. I think the game is better served by having that model gradually change over time. I wore T4, and then upgraded to T5, then so forth.
As seasons change, your character changes in a natural fashion. You look forward to new sets, commiserate with others when sets are weird (honestly, pally T3 and T5?), rejoice with them when they are good. Your character changes as you do things, and your gear reflects your accomplishments.
Gear is tied to a time period, and gear from that time period evokes memories of that time.
Cosmetic gear throws away all that. You find some set of gear that you think looks "cool", and you wear that. Or more accurately, all the teenagers will find the gear that looks the sluttiest and wear that. Yay for raiding with people wearing [Black Mageweave Leggings].
I guarantee that the vast majority of paladins will be wearing T2 Judgement from now until the end of time. Judgement is awesome, I have collected 7/8 T2 and an Ashkandi recently. I consider that to be the high water mark of paladin fashion, and wear it in town on occasion. But its time has come and gone. New tier sets will just not be as exciting as before when everyone wears the best of the old ones.
There are issues with gear art at the moment. There are too many recolors, diminishing the uniqueness of the art. Tier art is reused for off-spec pieces, so everyone looks the same, instead of having Tier sets being instantly recognizable.
But I think those issues could have been solved without cosmetic gear. I think cosmetic gear will prove to be a mistake in the long run. We play these games for a long time, and fashion needs to cycle, to refresh itself with new ideas. Allowing time to stand still, to grow stagnant and ossify, will only hurt WoW.