Great graphics doesn't make a great game.
Take Doom 3, for example. The graphics are great (from what I've seen in screenshots and trailers), but there is no story. It is only a remake of the first Doom with better physics and a lot of eye candy. I might be interested in playing this game, but I'm sure that in a few hours, I would be bored out of my mind.
To me, story is a key element of a game (any game). That's is what keeps us interested in playing.
KotOR had a great story, and I'm certain the KotOR II: TSL will have an even better one.