I think Nintendo have occasionally been worried about the lack of third party support. They tried and failed to get third parties involved with the Wii U. Darksiders 2, Batman Arkham City, and Mass Effect 3 featured a lot in the initial Wii U promotion, and were meant to signify that the Wii U would cater to more "hardcare" tastes. But it obviously didn't work.
The last Fifa for Wii U came out in 2014, which is kind of insane. You're right in that Wii U people aren't bothered about GTA5, but they probably do want to play Final Fantasy, Persona, Bioshock, Fifa/Pro Evo, Mass Effect Andromeda, Street Fighter, etc. That and there's the downloadable stuff they miss out on e.g Geometry Wars, Inside, Gone Home.
It's a different market but it's a market Nintendo need to tap into in order to compete. Kind of get the impression that if this is the succesor to both console and handheld, they're throwing all their eggs in one basket.