Dreamcast, Xbox, PSP, PC, iPAQ/Palm ... some have good content, some not. The common denominator is kick-ass nintendo games.
It doesn't matter if the system has good content of its own, the fact of the matter is nothing compares to nostalgia (for a time). So if you're going to bash the PSP for having a crap library, go ahead, but don't say it is a crap platform because people choose to play Nintendo games on it.