The problem with leaderless uprisings taking over is that you don't always know what you get at the other end. If you are not careful you could replace a bad government with one much worse!
The purpose behind terrorism is to instill fear in people - the fear that electrical power, for instance, will be taken away or the transportation system will be taken down.
It's such a great feeling to make people laugh. I know I've made people cry or want to slit their wrists, but to make people laugh is a very intoxicating, wonderful thing.