Comment by Someone

Because non-violent protesters can be a pain in the neck, too. You don't need to hit someone to really piss him of.

In some cases, just following the rules to the letter can be annoying enough to make the powers that be change things.

But yes, having some real threat as a backup has tremendous benefits. 'Nice government you have here; it would be a pity of something happened to it' works better of you have that.