I don't think the Boston bombers or people using trucks to run people over are geniuses. Even the Batman killer was building bombs in his apartment. It's not rocket science. You may reduce the casualties with a ban and confiscation but you still have handguns to deal with. Good luck banning those. And you also have not solved the underlying problem causing these violent ideations in the first place. So I consider that a bandaid, not a solved problem by any definition.