Well I don't think there's a problem with not finishing games. I think it just depends on the type of person you are. My cousin is like most of you; trying to experience all the games he can, while beating some, and abandoning others. I'm the complete opposite; I play very little games, but the ones I play get fully beaten, because I like to know everything about the game. After that's done, I move on to another game.
Beating a game also takes a lot of time....which most of us don't have. Games could be beaten in a few hours back in the days, but now it can take up to weeks. Omen, you don't suck because you don't finish games