I mean, it's hard to just say what is too much (and you can have too much). There is:
- Blood splatters in a fight. Can't have a good high def game if you just systematically remove blood and wrap all weapons in styrofoam.
- Violence to build character. If someone is a brutal villain, using violence helps show that.
- Violence just because. Games shouldn't just go all out trying to be as brutal as possible. Some games (Mortal Kombat, Doom) are based around it but it shouldn't become typical.
I hate when a game avoids violence just to lower the rating, but games shouldn't all be competing to be the most outrageously brutal thing in history.