The thing is, while this is technically quite easy to do, for mass market appeal, it has to support software on memory cards, *and floppy disk*, so that average joe ex-amiga user can snap up a "MobileMiggy", grab his box of disks down from the loft and start playing them (IMHO).
Floppy drive technology hasn't shrunk all that much, combined with the fact that the motor will take quite a chunk of power from the batteries, makes this quite an expensive problem to solve.
