Well, I've played all the classes to 13 at least twice. The Wizard is my favorite class at that stage, she used to be way ahead with Sleet Storm, but now it's still a little more fun than the Barb, who will be my main nevertheless.
I wouldn't say, that lvl13 balance matters much, but imbalance at any given lvl shouldn't be too drastic. It's okay, if the Skeleton King is a little tougher on a caster class than on a melee, but it shouldn't make too much of a difference, there shouldn't be things like "beginner" and "expert" classes(like in Dragon Age :P).
With this introduction I want to say, that I consider the Wizard the only class that you could die with on your first beta playthrough. So she is a little more fragile than the other classes and she doesn't make this up with damage. In this early stage! So, in conclusion, she is the toughest class to beat the beta with in the first place, but it isn't that much tougher to be a problem.
Way to ignore the issue being raised in the thread. If 'good' wizard damage is strictly inferior to 'good' every other class damage, then we have a problem. Getting better gear will not solve that.
A solvable problem. If blizz are good at something that will be balancing...
You couldn't be more wrong. WoW in general is great example. In PvE top heal/dps classes rotates form patch to patch, they always did. http://raidbots.com/dpsbot/ You can clearly see that same player, of same skill, with BiS items for his class can have a dps difference of almost 70%. Blizz games were never truly balanced and... it's not rly their fault, since it's almost immpossible to blance such huge games. I'd still say they do a decent job tho.