Yes, these are quite different devices ... I would estimate a factor of 100+ difference in price, and probably similar factors in terms of capacity, speed, power, etc, etc.
The API you're suggesting makes a ton of sense for the low end devices. I don't think there's a whelk's chance in a supernova of it coming to anything, though. You'd need the SD association to require it, and I can't see it being in the interest of any of their members. When the reaction to "hey, your cards suck for this other filesystem" is "your filesystem is wrong", I can't see them being enthusiastic about something this radical.
I do see that Intel are members. I'll try to find out internally if something like this could fly.