You do need to use your fingers to play. Sometimes, if you've been working very hard on the larger motions of upper body, shoulder, arm, and wrist, you forget to pay attention to the fingers. It used to be, perhaps, that people made the opposite error, too much time spent working on/thinking about the fingers and not enough on the rest of the body. But you do need a little impulse of the fingers to bring out a note. Practicing something slowly with finger staccato is a good way to get your fingers to learn to get on and off the notes quickly, and practicing like that will show you where you are leaving your fingers on the keys too long. Obviously you won't play like that in the end, but it can be a very instructive exercise.