Actually, I believe they said they want to have multiple viable builds for each class. One of those being, the melee wizard.... and they might actually pull it off if you look at some of the runes for the wizard. You aren't forced to make a glass cannon wizard and that's a great thing! It's incredibly boring to have a class pigeon-holed into a single spec/specialization.
You could make a glass cannon wizard though! If you forgo all of the defensive skills, you could pile on the skill enhancers and make a glass cannon. Sounds like a great system to me.