Tarantino is certainly into violence. I don't think he needs a reason to include it in a movie - more like it
is the reason for the movie, as far as he's concerned.
I've seen both parts of Kill Bill. In spite of some well known names in the cast (Uma Thurman, Lucy Liu, David Carradine, Daryl Hannah, probably others I've forgotten) it wasn't much of a movie. Thin plot, and that much violence is not entertaining. Not if it doesn't have a reason.
There was plenty of violence in
Taken, or
A History of Violence, or some of Charles Bronson's stuff (
Mr. Majestyk, the
Deathwish series) but at least in those movies there was a reason for it.
Ack! There's a
third Kill Bill in the works!