DBZ characters are one-dimensional.

Vegeta went from only caring about being the world's strongest, to giving his life for those he cared about.

Piccolo was an evil villain hell bent on world domination, then, he became a second father to Gohan, and has given his life to save Gohan, and risked his life multiple times for his friends.

Goku is pretty one-dimensional though, he never changes during the story.

They're two dimensional.

DBZ is just a cartoon. Fact. Just try and prove me wrong.

So what if they are, the still grasp more meaning than you and they can teach you something unlike some real people can