I've also thought about this! But Internet-Janitor is totally correct about all the technical stuff. I think it would require someone very familiar with both Decker and the specifics of 3DS homebrew applications in order to bridge the gap and make sure things run well on the hardware.
But if anyone ever builds a way to port Decker games over to run on the 3DS then I think I would be very fun and cool to make some at the correct size for the screens and then try them out! (Maybe someday...!)