>>43254620Because they put their Magnum opus and it's even better sequel on an ancient dying console that was torn completely open by pirates at a time when traditional portable gaming was struggling hard against the rise of iPhone gaming. Because it didn't sell well (for a Pokemon game), despite getting among the highest review scores including a perfect Famitsu score, Gamefreak took the lesson that they shouldn't put that much effort into the games and focus on just making what sells.
It's one of the reasons every gen after 5 has a new major gameplay gimmick.
