I agree. Having motors on a normal snowboard would be extremely useful. Perhaps have the wheel be retractable so it doesn't get in the way for regular downhill snowboarding. I think it'd be a challenging project because all of this would have to be waterproof and retractable and lightweight.
Depending on the resort, there are almost always times where some traversing is necessary, and most snowboarders will agree with me that this is the most annoying thing ever - unstrapping and strapping back in on the flats.