PPV has zero bearing on excitement... look at GSP's numbers FFS. PPV just means more casuals know the fighter. More time to jump on the champ's bandwagon means more fans. Which means GSP, then Hughes.
There's no universal standard for entertainment; its subjective, not objective.
Is jazz entertaining? Some folks say yes, others no. How about Beethoven? The Rolling Stones? Beyonce?
Does everyone agree on what movies are entertaining? On what books are entertaining? Even on what sports are entertaining? If not, then why in the world would you expect everyone to agree on what fighters are entertaining?
MMA fans are odd that way. Most people realize that different people find different things entertaining, that one person will like a movie like "Titanic" and hate "The Dark Knight", while another person will say "Titanic" is boring and love "The Dark Knight." But MMA fans seem to think everyone should agree on what fighters are entertaining and which ones are boring, as if it was something other than a subjective judgement.
The best you can do is count numbers of people who are willing to pay to watch something - it doesn't make that thing objectively interesting or boring, but it gives you an overall guideline. So "Titanic", which I found boring but which the wife loved, made a huge amount of money, so I guess I have to concede that not everyone found it boring. In fact, a lot of people found it quite entertaining. So what does it mean if I say "Titanic" was boring; it says more about me than the movie itself.
Same with GSP's fights - some folks liked them, others didn't, but overall more people liked them enough to pay to see them than most other fighters. There's no objective standard, its completely subjective.
This is standard in everything else; only special snowflakes think that everyone has to like the music, or food, or movie, or fighter they like.