>>39259637half of TPCi's work went to Masters and half of Game Freak's work went to Town.
The expect (nay want) the handheld/console games to die, so they're putting in less effort. Which as a self-fulfilling prophecy, will doom the game to poor sales, at least compared to its predecessors.
When it does poorly, they will take this as proof, and put even less work into the next game. This creates a perpetual cycle until the deathspiral finally crashes into the ground.