I think its a problem with going from whats in their head and actually vocalizing the thought process.
They don't read enough books.
EDIT: Oh, and what's wrong with Solo shooting first? If you are holding a gun on someone, and they are going to be possibly killed by the person you are attempting to bring them to, then I'd expect it. I'm just surprised Greedo was so lax. Perhaps he had a fit of ye olde evile dude monologuing syndrome. (Stole that idea from The Incredibles.)
I DO TOO READ BOOKS!!!!!! go ahead, ask me about WWII. (my favorite subject..... well, in a tie with SW)