This thread shows how many people really love Nintendo games at heart. They want Nintendo's games on their console of choice. :)

OT: Their hardware sales are a major source of income for Nintendo (Wii comes to mind)

Very true and they don't have to split the profits with the Said console they are publishing on. I think Used games really gave us these broken games, because they have figured that they can only spend this amount of money and time with out taking a massive risk of closing their doors. People love to deny it but Gamestop really put a nail in it.

nintendo philosophy.

There games will get worse.

Because Nintendo's games are so good that, once people play them, they won't want to buy sny other third party games. Nintendo would actually corrupt any console they design games for. People would start calling the Xbox or Playstation the "Nintendo". Suddenly, there would be nothing but "Nintendo consoles" on the market and the wannabe cool kids would quit buying them at all.

Either that or Nintendo fans who hate third party games will hate Nintendo because suddenly THEY are a third party and kill themselves. Either way, no good would come of it.

Cause they will probably end up like Sega

Still won't save SONY if they keep having losses like they have almost every single year for a decade now. Developing a console is both time and money consuming, let alone producing and selling them, so going third party isn't as impossible as often pictured for them, especially if some future console flops.

As for Nintendo, they generally design their games first and then the hardware they would need for them, which is how motion controls, dual screen and tablet controller came to be. This would be impossible if they can't design their own hardware, and the quality of their games may suffer in the progres. Nintendo would also stop producing smaller game series since they can't generate enough income on their own, which would probably be the final nail to the coffins of F-Zero, Metroid and Starfox, to just name a few.

And from a more general perspective: Is there even enough of an audience for Nintendo games on the SONY/Microsoft consoles? Doesn't really look like it, really. So it might actually get even worse for them if they went 3rd party.

No it just mean that first party games are usually better than third party games and that's true for all consoles. Sega was better when they were first party... Developping for different hardware architectures is not an easy task, it takes lots of time and money to have the same experience on each different platform. In the end you need a lot of sales before you make any money and you will take a lot less chances on different gameplay  and way of playing a game to achieve these numbers of sales. In the end you loose creativity in the process. Less creativity = worst games in the end.

There are about 746 reasons, but you only have to google it to find 1,546,391 opinions on this topic.

That's really not too smart. If you abandon consoles you should abandon handhelds as well.