I originally thought that too but now looking at the stats Mega evolving is the only solution from a numerical stand point. If you had a team of 6 permanent megas with those ridiculous stats how OP with that be? Also there needs to be a consideration for things like eviolite. So pokemon like Steelix now have a true evolution. That would make it OP has hell with eviolite, not to mention how bulky pokemon other pokemon would become.