Easy. One Line of Dialog -- Thank God We Invented the...Whatever Device

From a Chud interview with Michael Bay:

Some of these characters have pretty silly names. How are you going to explain names like Jazz and Optimus Prime?

Well, I'm not going to tell you, but we do justify it. I mean, we have logic stuff in the script to explain why we say it.

The mind of Michael Bay, ladies and gents: "Logic stuff." People wonder who makes these movies. There you go. That said, the new Transformers trailer is completely over-the-top awesome in so many ways I can't even begin to describe it. GIANT. FRIKIN'. ROBOTS.