For a very simple reason Joey.
Manny is a proven PPV draw. Marquez is not.
That speaks a lot about their respective fanbase and popularity.
Manny was already a major PPV force when he fought Oscar.
Manny is still hugely popular since his knockout loss. Ever imagine Marquez pulling 1 million PPV buys or something close to it? I bet Manny still can even if he fights Guerrero or Bradley. I'll cut my testicles off faster than El Clitorish if Marquez can pull 300k fighting any of those guys. Did that stunning win earn him the confidence of the promoters that he is primed to headline a major PPV event? I don't think so.
Pac was not a major ppv draw when he fought Oscar.
Pac-Diaz did not sell 400k buys.
It was Pac's win over Oscar that doubled his popularity.
JMM is da man right now to the Mexicans.
He will command huge dollars if he fights Rios or Khan or Garcia .
He does not need Pac.
Pac needs him for redemption.
Who has more leverage?
Establishing the biggest PPV numbers down the lower weights with Morales and Marquez, sure that doesn't make Pacquiao a bankable PPV attraction. In 7 years, Oscar didn't make 147 lbs. but he did go down for Manny. Hell, he wouldn't have done it with anyone else if the other guy was not well worth it. It was a clash of two major PPV fighters, outside of Mayweather, who happened to be both ultra popular and charismatic. Hence, "The Dream Match" title. Can u imagine another popular fighter who would fit "The Dream Match" title with Dela Hoya at that time? Pacquiao was making lots of money for Arum and he was a consistent PPV hit. Pacquiao made those numbers possible with crappy undercards. His rematch with Marquez was the highest grossing PPV match below the Light Welterweight division.
JMM is definitely the man of the hour but it's hard to translate that to PPV numbers. Before the fourth fight with manny, Marquez bored a few crowd with a certain fighter whose name u couldn't spell. Suddenly, he is an overnight sensation? In Mexico maybe but i see his marketing power to mainstream fans no different to Ron Tarver after upsetting Roy Jones. Fact is, marquez is not an established PPV attraction. Thus, he couldn't command more than his true worth. And his true worth will only be validated if he fights Manny. So u think he has the leverage? Manny is still under contract with Top Rank til 2014. He's gonna fight anyway with or without Marquez. Arum and Pacquiao had already given Marquez the cold shoulders in the past when he priced himself too high in their proposed immediate rematch. Who struck gold after that? Manny made a killing with Morales while Marquez had to travel to Indonesia. Manny could still earn 15 to 20 million dollars fighting Rios or Bradley. How much do u think Marquez is gonna get fighting Guerrero? Who's the promoter brave and stupid enough to put that crap on PPV and guarantee Marquez 10 million? Remember, the promoter is on manny's side. They still call the shots, not Marquez. if Marquez insists he deserves the higher pay, then, Arum will just tell him to fight another man on PPV and see if he measures up to Manny's PPV clout.
Naturally, we would say that the only road to redemption is Marquez. But Duran showed us, after getting knocked out cold by Hearns, that the road to the top could also be someone else. In the end, Duran is still regarded with a better legacy than Hearns.