He could have LEAST changed it to one of the cool transformers, like Grimlock or Starscream

Awww, come on! Optimus was the MAN (er..robot). He was like my role model when I was a kid. Starscream, while a cool name, has to be one of the most annoying characters ever. I hated that guy

By the way, I practically cried during the movie when I saw that they killed Optimus Prime. I can only imagine the trauma this guy went through!

*edit*
ps- that wasn't Grimlock you linked, it was Grapple. This is Grimlock.