Don't be mad because the barb is the ultimate badass.
Is it wrong to enjoy diversity?
I've played about 10 levels each of Barb and Wiz so far, and I enjoy both, but the Wizard is definitely more of a support class. Lots of area spells that immobilize, repulse, or do AoE or DoT in a large area. One wizard by himself is a little hit-and-run to play alone, but if you pair them they suddenly become engines of destruction. One Wizard really doesn't have enough mana to finish off mobs by himself, but he can do a lot of total damage because most of the spells are AoE. Add another Wizard and suddenly you're carpet bombing. Plays really well with Demon Hunters too from what I've seen so far. Run into the mob, Frost Nova, spam some AoEs and run back, with the Demon Hunter laying down supporting fire the entire time.
Granted these are just my impressions from my first few hours of play. I'm basically a n00b since I never played D2.