This is what he had to say,
When comparing at-wills for controllers, the wizard has some issues. His at-wills focus more on damage than control. The consensus is that controllers need a little more, well, control in their at-wills than we've handed out so far.
Vanguard's lightning is what I'd see as a baseline controller at-will, with scorching burst slightly *below* baseline. That little extra bit on vanguard's lightning is precisely the kind of thing that makes controllers go - they limit/mess up the enemy's plans.
Now, this may seem pretty annoying - WotC released stuff that was too weak! However, I think it's actually a strength of the meta systems of 4e. We've never before had the ability to so clearly compare classes/roles and, when necessary, make adjustments. It's a lot easier to listen to feedback, gather hard data, and make comparisons between powers when we have a unified power scale.
The interesting thing is that this issue really only rests in the at-wills. Encounter and daily powers are fine for the wizard.
The controller role is perhaps the one that took the longest to really develop. There's a reason why there's only one in the PH. For a long while, the role was defined by its ability to attack multiple foes. That definition never sat well, since it clearly steps on other roles and archetypes. We'd never want to prevent rangers from firing multiple arrows, or a fighter from striking everyone adjacent to him.
Over time, the controller definition morphed into the opposite of the leader. If the leader sets up his allies and encourages teamwork, the controller screws up his enemies and hinders their ability to work together. The area damage aspect of the controller does play into that (it makes bunching up a bad idea) but in practice controllers need a little more to embrace their role.
It's a subtle point, and in the grand scheme of things I don't think a PH 1 wizard is crippled compared to the PH 2 classes, but it is a sign of the subtle adjustments we're likely to make to the game going forward.
There's already another thread talking about the implication of his words but I'm interested to hear what everyone from the bloggersphere has to say about this.