When the option is available I prefer to play on a 50" screen instead of a 3" one. My father-in-law liked watching me play ExciteTruck and Excitebots while discussing the games or having other conversations better than actually playing. If I'd been playing on a DS while talking it would have been awkward and made me seem antisocial.
While some games are designed with the DS in mind: Henry Hatsworth (Dual screens), Brain Age (Stylus input), etc, I never saw the necessity of NSMB being on the DS other than portability. It used the touch screen for powerups, but that could have been done in a variety of other ways such as SMB3 or SMWs systems.
Before the Wii was announced I'd hoped for the next Nintendo controller to have a small screen similar to the DreamCast for games like Four Swords, but since that didn't happen I guess simultaneous multiplayer is nearly as good.