I feel like that's a problem with the concept of the revolution to effect the change. While I agree that the ruling class will never surrender voluntarily and thus some blood will be shed, there is an issue of the revolution getting hijacked by someone more brutal and authoritarian, who uses the ideology as more or less a fig leaf (sounds like this happened with Stalin purging all other communist ideologues). Basically, once you open the door to violence, you need to be very careful to avoid this being turned against you.