These MMA guys are sloppy as anything. Just rubbish from Aldo, jump in with your chin floating in mid-air. McGregor did what any half-competent striker would do and plant a big one right on the kisser. Not a great knockout by any stretch. Same with that Rousey fight the other week, it's easy to look good against someone who walks in basically saying "go on, hit me, I'm here!".
Entertainment for the unassuming general public, I guess. A far cry from top-level boxing or kickboxing, though.