The Nintendo Wii was seen as being irrelevant by many people inside the industry, and some people didn’t think it had a chance of selling as well as the Gamecube did. This resulted in most third party publishers dedicating most of their "Good" developers to HD-Console projects, and most "Main/Big" third party games were started well before people realized the Wii would be successful.
In the next generation, I don’t expect nearly as many people will discount Nintendo before they announce their system and I expect there will be a fewer technical differences between the consoles which will result in Nintendo’s next system getting far more support from "Good" developers.