I think lots of guys saw a different fight than I did. That blow to the back of the head happened while Mir was working a sweep to put Lesnar on his back. The call that got the fight stood up favored Lesnar as much as Mir. It gave Lesnar the opportunity to strike and take Mir down again and avoid the sweep. Lesnar never had Mir in any real danger. He scored a few takedowns and noogied Mir, but never hurt him. Lesnar makes a lot of fundamental mistakes like not underhooking on the ground which crafty fighters can easily exploit.
In regards to banning submissions, don't be surprised to see them start disappearing. It will start with spine and neck locks and then probably move to twisting knee locks. I'm not sure of the statistics, but when injuries are had by submissions, it is often by neck cranks and even more often by twisting knee locks.
You're missing the marketing element of the big picture. The UFC wants to be mainstream, so over time more rules will be added and more violence removed. In the earlier UFC's there were no gloves, no weight classes, and no time limits. All fighting techniques were legal except fish hooking, biting, and gouging. There was one fighter victorious at UFC 2 that won mainly due to repeated groin strikes to his downed opponent. The UFC suffered an American pay-per-view ban in the later mid 1990's due to it's violence. To keep the law on it's side, the UFC must appease politicians and I think the UFC did so by aligning with the NSAC.
If you want something a bit closer to "real fighting", I refer you to 'Rio Heroes'. It's a bareknuckle that league has rules, but they are much fewer than the UFC.