But Nintendo also wanted to attract third parties to the Wii U, and while that went well initially, once the Wii U started lagging in sales and third party games had bad sales, third party support dried up.
They even listened to third parties when designing the console: http://nintendoeverything.com/gearbox-nintendo-has-listened-to-wii-u-feedback-controller-specs-will-be-awesome/
“We were early in seeing what was happening with the Wii U and we’ve been able to give some feedback. They’ve listened, and I think we’ll see some cool stuff that we’ve had some influence over. I think the final controller specs are going to be awesome.”
A lot of third parties were on board in the beginning: EA, Ubisoft, Activision, Warner Bros., THQ... But sales were bad, so they stopped caring for the Wii U.
http://www.gamesradar.com/e3-2011-wii-u-getting-support-from-ea-ubisoft-thq-and-other-big-third-party-devs/
So it's not that much that Nintendo doesn't care about third parties, it's just that the people buying their consoles don't seem to care about it. So, unless their consoles actually sell very well, third parties aren't going to take off, unless their games specifically target the demographic on Nintendo consoles (platformers, party games... tend to sell well on Nintendo consoles)
