Have they tried ???
To have someone like Sakamoto-san talk about Tomodachi Collection and [Metroid's protagonist] Samus and share his experiences really is a way that we're trying to encourage developers to open their mind to do different things. On the other hand, the interesting thing about this business is that developers love to create technically advanced games, and very visually stunning games, but the fact of the matter is not all of that content is selling exceptionally well either. Look at the most recent NPD results.
I'm not sure how much was invested into a game like Dante's Inferno, or how much is invested into a game like BioShock 2, but if that sales level is the best that they will do in a particular month, and it'll fall off rapidly from there, then those games aren't going to pay off their investment. So to me, it's a much bigger question than 'why aren't developers creating core content for the Wii?' It's a much broader question: 'How can the development community create content that will strike a chord with consumers and be financially attractive?'
...For us, it is important that third parties bring their very best content to our platform. You could say 'Why?' It's because... well, let me focus in on the West. There are 28 million Wiis out there in the marketplace. We know, based on our data, that we've got consumers from 5 to 95 playing on that platform. The fact of the matter is we know we create great content for younger consumers, we know we've got great content for more casual players, and we want fantastic content for that more active player who loves Metroid or Zelda but maybe also wants something like a BioShock 2 to play as well. And we also recognize that we don't create that type of content ourselves. We're not good at it and it's not a key focus area. So we want that content on our platform, so we have to court third-party developers and encourage them to make [those games], but it also has to be financially viable for them as well." - Reggie Fils-Aime
http://www.industrygamers.com/news/nintendo-to-third-parties-weve-done-our-job/
I agree with Dante's Inferno. The cost for the publicity and the game probably won't be covered by the sales, but C'mon Nintendo can make things like Bioshock ... if they try.