Let's look at this another way...

People are always going to kill people. You can enact laws to punish people for doing it, you can try to teach them right from wrong and ask them not to do it, but inevitably people will still kill other people.

By your argument, it's futile try to stop murders from happening... so we should just let it happen and go on with our lives or try vigilante justice and hope we get rid of the murderers ourselves.

Umm, what? lol

I know it's a ridiculous comparison, but just because some people will always do bad things doesn't mean it's futile to try to stop it. At least Evony is trying... even if they're being slow and inefficient, it's better than nothing.