There is several reasons why Nintendo consoles don't have good 3rd party support and there is nothing with bad relationship, its all about money.
1. 3rd party is selling bad on Nintendo consoles. Fact, people in most cases buy Nintendo consoles to play Nintendo games, same couldnt said for PS3/Xbox360 and espacily now with X1/PS4 where majority of people buy console actuly to play 3rd party games. Because of that 3rd party games always had much worse attach rates on Nintendo console than on PS/Xbox consoles, there some exemptions like Just Dance games, Lego Games and similar..
2. I think Nintendo never invest such effort to have great 3rd party support like PS/MS are doing because they thought they dont needed to do thatm, and even if they dont have strong 3rd party support they can carry platform alone. Wii U prof them they were wrong.
3. Different hardware (power of hardware, difrent architecture and hardware, controls...), Wii and Wii U were much weaker than competition and they had motion controls and tablet controller (with Wii U that wasnt relly big problem). Difrent hardware makes 3rd party much harder to make ports.
4. Bad sales of console and low instal base. This goes only for Wii U, if we look Wii U at launch actually had solid 3rd party support, but fact is that after terrible sales in first year all abandoned them.
Wii U basically has all those things that I mention and that why dont have almost any 3rd party support. Saying that Nintendo with NX could fix most of those things and certainly make it much more attractive platform than Wii U was, for instance we can expect 3rd party support of level Game Cube had.
I expecting that NX will have similar architecture and power to PS4/X1, that means easy, cheap and fast ports, Nintendo will definitely invest bigger effort to have much better 3rd party support than Wii U had, and NX will definitely have better sales than Wii U had.







