Yeah, I thought it would probably be some rules or whatever, but I was in an irky mood today when I logged in and this thread just reminded me of how unfair it is that Peter Cullen got bumped down the credits like that.
I'm in no way though suggesting Michael Bay did it that way because he considers the human (and dog) characters more important than the robot characters, but I'm sure some might decide that's the only reason.

But I do know that - and I'm finally steering back to the actual topic of the thread here (   ) - that if Cullen (and Welker) got actual cameos at least they'd get a credit in the main cast listings, and perhaps maybe one of those nice single name credit screens (I just don't know the official term for those things dammit) too.
So bring on the cameos, if only for that extra layer of credit recognition for the original Optimus Prime.  

 

I would wish be in place of Peter Cullen in this moment  
Yes, indeed, it's cool idea! I would be glad to see this scene   By the way, it seems, as I heard somewhere here, Peter Cullen really can drive a truck  

 

I know that feel, bro.

 

Peter Cullen and Hugo Weaving should have been given top credit.

Not those ingrates Shia LaDouche and the Chick of the Movie. John Turturro though deserves top billing.