This is going to sound snobby, but the main reason third parties stear clear of Nintendo is Nintendo just is on another level of quality compared to many third parties. Hence why they don't sell as much on Nintendo platforms. Sure, you could argue the strength of IPs has something to do with it, but these Nintendo IPs are successful for a reason - they are the faces of quality games that have poven to be enduring to Nintendo gamers and enabled them to be popular in the first place. Nintendo doesn't put some spell over its audience compelling them to buy their games. They're simply at a level of quality that translates to sales.
What third parties need to do if they want to do well on Nintendo platforms is really look at the elements of Nintendo's games that sell, emulate those features, and create some great products for their consoles. Not just crappy rushed ports, not afterthoughts or spinoffs by devs' B teams, but fully-fledged, quality software that has great and enduring gameplay. As long as these devs really put their passion into making great software, I really do believe that their games will sell very well. After all, there were plenty of quality NES and SNES third parties titles that sold strongly. Why couldn't this happen again?
"We hold these truths to be self-evident - all men and women created by the, go-you know.. you know the thing!" - Joe Biden
