G'day Steve,
One huge thing to watch out for is when our policies end up hurting our responsible contributors more than the vandals and trolls they're supposed to protect us from. If every new contributor is guilty until proven innocent of being a vandal, POV warrior, linkspammer, copyright violator, or non-notable vanity article pusher, we're going to turn off and drive away a lot of new contributors. (The only way to make it worse would be if the process for proving yourself innocent involved following -- to an absolute T -- a bunch of elaborate policies which new contributors aren't likely to be aware of.)
You speak as if we don't already do this ...