In that case many players wouldn't even afford to travel to the tournament in question, which would lead to a drop in the field quality, which might also reduce the attendance.
The players on this level need all the economical help they can get.
"Certainly the most talented individual, the most well-rounded
... to play this game." - Jason Goodall
We should be appreciative of Federer though, because we will never see anything like him again. The fact he can still compete for slams ever after the erosion of his physical skills is really a greater testament to the natural talent he has than the period of time when he was dominating the tour.