I think playing gray, that is, neither light nor dark side, is the most realistic alignment in terms of human nature. Most of my characters are gray during class stories, because I always pick choices a rational person would, and any lightside points I get end up balanced out by DS points from other choices. It seems like, to be exclusively LS, you'd have to play like a sickeningly naive, sort of retarded goody-good, whereas exclusively DS would be some psychotic animal off the leash. Story-wise, they're not realistic portrayals of anybody.
An example, the LS choice at the end of the JK story is to spare the Emperor, I picked it with the intention of restarting the conversation just to see what Scourge would say, and he basically called me a *********** braindead moron, rightfully so. Likewise a lot of DS choices seem to be "being an insane, mass-murdering ***** just for the sake of it", even when it would be detrimental to you.
