I've seen lot of people do pixel art in games and have some hi-res smooth rotations and stuff in them. This is when i'm asking the same question.
I don't like too simple pixel art as it's in Super Mario 1. I like more how things look in Super Mario 3.
In 90's I used to do long animations with this icon software called Microangelo. It was fun to see how just one pixel can change the whole thing.
I think people like to do pixel art for the same reasons as people like to draw manga and make things look Japanese. In the end most of these drawings just look awful.