These people wouldn't complain about Nintendo's output if the Wii U would also get all the third-party games but since these games don't release very often on Wii U, many people think that Nintendo has to release more own games to compensate the lack of third-party games.
If you plan to buy a second console only for first party games, a Nintendo console can be as good as a Playstation. Same if you don't care about third-party games.