Having watched the movie again as a grown up, I gotta say that's the one thing I don't like about the movie. Optimus' death was pretty much Hot Rod's fault, then Hot Rod becomes the next Prime. Craptastic! That and I've always wondered if the Matrix chose Hot Rod only because he was the first to touch it after it fell from Prime's hand. Take those two parts away, though, and it's pretty much a perfect movie. Well, perfect through my 1980s-fan boy eyes, anyway.
Don't get me wrong, I generally liked Rodimus. He was a unsure, newbie leader, Optimus' opposite number. If it wasn't for the fact that he was ALWAYS such a vagina hole around Ultra Magnus, I would have really liked that little squirt.