There are some really good young players with amazing potential: Kachanov, Thiem, Zverev, Medvedev, Tiafoe, etc. I would like to see them have an opportunity to fight it out at the top. I don't see that happening if the big four rest up for their best tournaments. I don't even know how Federer is allowed to do this. I thought ATP had to play masters 1000 level tournaments unless injured.
The big four already killed off the last generation of promising players -- Berdych, Nishikori, Gulbis, Gasquet, Tsonga, Monfils, Roddick (still only 34). I would hate to lose another crop. I think the ATP needs to force players to play a reasonable schedule.