I was part of a gaming community where a number of members were very vocal fans of Nintendo (myself included). One, in particular, took things a bit too far compared to others, however. Their rhetoric was as follows: if a game company was releasing a game on the Wii, that company was the bee's knees, and if they weren't, fuck 'em.
This rhetoric has always troubled me, and I'm more than certain that they weren't alone in this way of thinking. Here's the thing: most of the time, game companies know what they're doing. They know that there is money to be made releasing games on the 360 and PS3, and that some games won't sell as well if given a release on a Nintendo console.
[sub]Pictured: Not one of Tecmo-Koei's smarter moves[/sub]
Take, for example, Samurai Warriors 3, one of my favorite games. Tecmo-Koei saw a bull market in Wii owners, who, at the time, were massive in number and outnumbered 360 and PS3 owners. It sounds like massive returns on paper, but in reality, the game sold less than anticipated. There are some reasons for that: first, that Dynasty Warriors games and their spinoffs already had a reliable source of income from PS2 owners, the PS2 being the system the series originated from. Cutting Playstation owners out of the equation in exchange for an untested market left little room for error if their bet didn't pay off. Tecmo-Koei only managed to make coin off of the game by releasing an enhanced remake of the game for the PS3, and since then, has not done much for Nintendo consoles aside from the odd Warriors spin-off game that are safer bets instead of main entries in their series.
[sub]Pictured: Money for Nintendo[/sub]
Not that Nintendo is hurting for a lack of Dynasty Warriors games, or most other third-party franchises that have opted to stay with Nintendo's competitors. Nintendo can continue on as a force to be reckoned with in the games industry because they have something that Microsoft and Sony lack: a combination of seniority and recognizable faces. Even if the Wii's lasting legacy is not one to be the most proud of, Nintendo still made off like bandits because of the likes of Mario, Metroid, Super Smash Bros., Pokemon, Animal Crossing, and so on. Third party franchises help bolster Nintendo's profits a bit, but without them, Nintendo can still expect to sell off tens of thousands of copies of Mario games, because their core base will spring for Mario games when they are available. That same core base, more often than not, will also have another console to play games that would otherwise be unable to enjoy should they only have a Nintendo console: another friend of mine loves to play Minecraft with her friends, and after shutting down a personal server because she couldn't afford it anymore, she continues to enjoy building with company thanks to the 360 version of Minecraft, at least when she's not playing New Super Mario Bros. U with said friends.
The long and short of it all is that not everything can be for Wii or Wii U, because third parties don't want to risk losing money with a market that may not buy their games. It's okay, though, because Nintendo will continue to be in business, so long as they have Mario and company at their beck and call.