Why do we need Control.Monad.Instances?

Hello, I forgot the reason why we need Control.Monad.Instances which exports orphaned Functor and Monad instances for ((->) r), ((,) a) and (Either e): https://github.com/ghc/packages-base/blob/master/Control/Monad/Instances.hs Can't we just de-orphan these instances by moving the instances for ((->) r) and ((,) a) to GHC.Base and by moving the instances for Either to Data.Either? Regards, Bas