I blame the lack of wizard control features. If wizards had increased range or size with their powers, the powers could be on par.
It helps a bit once they get Spell Accuracy.
Yeah, this is what I think a big issue is. Built into the basic class should have been control features that enhanced what they do. Not feats later on or a paragon path, but core abilities picked up at level 1. The implement mastery stuff a starting place for what they should of had, but unfortunately its a ending place.
Also unless one of these control features was increased damage with AoE attacks there should not be any powers from classes in other roles that do more AoE damage at the same levels as a wizard.