Yeeesh. people are always complaining. usually the weak ones.
Anyhow, I think that the guards being invincible was a code mistake. I'm sure the immortals wouldn't allow a flaw like that to go on. Besides, it's the criminals that make the game fun. Also it makes justice work a little harder and actually should be fun for them since this is just a game.
If there weren't any criminals then there would be no justices.. and the game would be seroiusly boring. I'd go play another one.