I agree completely mverta. That is how it was taught to us in my Film Theory class. My prof is a huge Star Wars fan and we had a whole segment devoted to the "space opera / space western" genre where Star Wars was the main event. She can't stand what Lucas has done to the films (she must be pretty excited about the September release).

Han was a cowboy. He dealed smuggling drugs (Star Wars calls it "spices") and other illegal paraphanalia. He lived in a rough and tumble world where he would be shot dead if someone was given the chance. He knew that and blasted away Greedo. It is of no consequence to him. Better safe than sorry.

And like you said, if anything was done in cold blood, he redeemed himself during ESB. Lucas is just an idiot. We know his films better than he does.