It's known that third-party games are relegated to the second place when it comes to Nintendo consoles. Now compare first-party sales of both consoles and you'll know why.
3DS released without known Nintendo software to back it up, what happened? SSFIV 3D was the best selling game for quite a long time, and that was quite an old game when it released on the console. Wii U released with NSMBU, which had some crazy attach rates. You can see where that leads. That's also the reason current 3DS third-party releases are also selling much worse, since the console is being supported with Nintendo's heavy hitters. Sony has clearly no first-party presence, so third-parties dominate. MS is similar, but it has a few big hitters, which didn't show up on XOne's release, so it'll also have a big third-party presence on launch.