They needed to transform into stuff!
I enjoyed it over all. It had some bits that made me laugh. But it really lost a lot of potential for humor by not including that idea. Like maybe Megatron becomes a gun, and just sits on the ground. Or maybe Prime becomes a truck and we show Megatron or Starscream saying "Huh, now where is Prime? Maybe that truck that came out of nowhere that is the same colors as him saw him!"
Yeah, I know, not that good, but I did just come up with them off the top of my head, and I think they're an integral part of any TF parody.