I'm not sure I would want to hear Feldstein sing Cinderella, but she could probably sing the Baker's Wife pretty acceptably. But I did suggest to a friend a few nights ago the Platt-Feldstein idea. For one thing, they are closer to the age that those characters (it would seem) are supposed to be, although this is just one of those things we have to accept in the show. Even with the later adjustment in lines, it still never makes sense or almost never makes sense that the guy playing the Baker is the brother of Rapunzel when those events happened when he was "no more than a babe." Lines in the original seemed to indicate that Rapunzel was 14-15. But the sense of desperation would be much less with a 20-25ish Baker and Baker's Wife, even though they might well feel desperate if they had been married for four or five years and had been trying all that time. But younger actors probably have some trouble conveying that.
I thought you were probably being tongue in cheek, but sometimes it's hard to be sure.