I don't deny there have been excesses.
I never saw a classmate with more than a bruised ego in my experiences, and the sound of someone else getting a couple of monitored whacks, was a great deterrent to others.
Just kicking them out of school creates more problems to society than teaching them that actions have consequences throughout life. They don't get that by sending them home to MTV and the internet and their buddies basement.
Are you from the UK?