I think I missed that one in the movie. Or I forget when they said that in the movie. They never gave a clear answer I think? Can someone explain this to me?
Because earth's old name used to be funky party planet. All types of life forms landed their just to get down.
Now that i think of it, isn't Optimus' speech at the end of TLK basically the exact same as the one at the end of the first movie? (Humans are brave, all remaining Autobots come here, etc.)
You're 100% right. Also in the trailer they made it look like that line had some weight to it. In the actual movie the line is just said in an introduction just to sound funny and worst of all we never get a proper explanation.
I think the only reason Bay cast Hopkins is so he can have him say things you would never hear him say in another movie ever. For example that is a "bitchin ride". I that was the line anyway.