I know there's very little chance that you'll do this, but I wanted to address the possibility anyway.
Peter Cullen was the perfect (and perhaps only) bridge between the classic incarnation of TRANSFORMERS and its rebirth in 2007. In terms of the role, Peter Cullen brought a warmth and heart to Optimus Prime that wouldn't have been felt if a more "studio-friendly" actor had been hired. Only Peter has the ability to balance authority and tenderness at different intervals so beautifully. Simply put, when Optimus speaks, we want to follow him - TRANSFORMER geeks and regular audience members alike.
It went beyond fuzzy nostalgia; Cullen's presence helped the movie in so many ways, and it didn't affect the box office in a negative way either. Lose every other familiar facet of the TRANSFORMERS universe if you need to, but please don't lose him.
Thanks for putting up with my fanboy rant. I try to keep them to a minimum.