Two thoughts here. In a fight, GSP lost plain and simple, he took the most damage and was hit harder than he gave. But in a match, he won based on points.

GSP, to his credit fights to accumulate as many points as possible, that's why the peppering of jabs, trying to score. That's also why he almost always goes the distance, he plays a calculated game and doesn't take a lot of high risk, only is the opportunity clearly presents itself, he will go for a finish.

In answering your thought HH on main fights not as entertaining as lower fights on the card, I think it's because the guys fighting on the lower fights want to prove something to climb the rankings so there's more of balls out chances, they may take higher risks in exchange for finishes. Whereas, the main event guys may not want to lose their spot and play it safer. Of course, this doesn't apply to all, but I think it might play into the minds of some of these guys.