If Mayweather-Pacquiao doesn't happen....why does a Mayweather-Cotto fight not interest people?

Should *knock on wood* Mayweather-Pacquiao not happen, why aren't people demanding a fight with that has Cotto defending his title against former WBC 154 lbs titleholder Mayweather in a Vegas megabout? Yes I know Pac annihilated Cotto, but back in the 80's Hagler-Leonard-Duran-Hearns fought each other and some of them were each others sloppy seconds (i.e. When Hagler fought a competitive match against Duran who was destroyed by Hearns in 2). So why aren't fans calling for this fight? I know ppl wanna see May-Pac, but I think Cotto vs Mayweather would be an awesome since I know Cotto has never liked PBF even since their days as 140 lbs stablemates at TR. F*** Margarito-Cotto or Cotto-Chavez Jr., Mayweather-Cotto would be a kick as.s. fight and hopefully the Bobfather swallows his fat pride and makes the fight happen.