Reigns retaining the way he did was stupid. Rollins isn't going to get booed. He could beat up Reign's kids and the fans would still cheer him.
Having Reigns win that way limits the damage done to AJ who has been doing well in the merch stands. Having Rollins come back last night was a way to send the crowd home happy and end on something people enjoyed, albeit something likely to end up meaningless in terms of storyline and results.
I hit the sack before the main event last night because I don't personally care, but I watched it today after hearing it was a MOTY contender from some (it wasn't). But it was decent. If they keep pairing him with people that he has good chemistry with, things could be a lot worse. They aren't changing their mind until merch sales make them and the crowd stop being so hot for matches involving him.
Yes, it was mostly due to hate for Roman, but the crowd blew the roof off the place multiple times during that match. Money Mayweather doesn't sell all those PPVs because people love him.