I think we've already got diversity, just not balance between the items. Your system is going to have the same issue with energy scanner that the current system has, namely that everyone needs one to be compe!@#$%^&*ive. You'd also find yourself falling into the slot trap because of game restrictions. You can only have 1 SLD, 1 bomb, 1 gun, 1 brick, 1 x-radar, etc.