I like the original line simply because it shows what a close relationship has been built between Luke and R2. Both have become very reliant on each other and the use of a more friendly and comforting "joke" to describe what almost happened shows how much Luke cares about R2. Instead of just pointing out, matter of factly, that he almost was recycle fodder, he tried to lighten the mood and calm the droid down a bit.

It's like what parents do after a child has a nightmare (maybe it was just my parents)... they try to lighten the mood to take your mind off of what you just dreamt about. I think it's a very applicable analogy here.

Now, I gotta admit that I would love to see a cut scene with Chewbacca crying on a shitter in the Falcon. Or, better yet, he gets so jostled and bent out of shape by something that happens that he curls into the fetal position on the cockpit floor of the Falcon much like Jim Bakker in the back seat of the car on the way to his trial.