Exactly. Finishing the pattern does not in the slightest way indicate a "love" for the job. That's like saying a showjumper must hate show jumping because he doesn't jump the course when his rider falls off. A horse that finishes a barrel pattern has it SO ingrained into his head, he MUST do that, or bad things will happen to him. Bringing human emotion into it is silly, horses do not think like we do.
As for the reining horse, I'm sorry, but that's just as silly. That's like saying if he had a rider on him, he wouldn't do it if he didn't like it. It's called training. It has nothing to do with human emotion - you shouldn't have to be touching or riding your horse to make him/her do certain things.
Show me the video where the rider falls off and the horse immediately stops and waits so as to avoid causing any further injury to his rider due to his good training and I will be FAR more impressed.