Maybe so, but scheduled doubleheaders in the last few decades in major league baseball have become as rare as hen's teeth. The main reason is that the owners have to squeeze every last nickel out of their customers in order to cover the insane salaries they pay their players.
I don't know if Banks would protest the lack of scheduled doubleheaders if he were playing today. It wouldn't be politically correct from either the players' union or the owners' point of view.
Banks would probably love the idea. It’s highly unlikely anyone would act on it, but I think if the Cubs proposed it as a one-time thing in Ernie’s honor, the MLBPA and the MLB owners might just go for it.