I'm talking about 3rd party support. Maybe Nintendo produces their best 1st party efforts when they have serious competition, but that gets canceled out by the fact 3rd parties leave. So do you want 3rd party support like the NES-SNES, or do you want an N64-GC with terribly 3rd party support but perhaps better 1st party stuff? I don't think 1st party software on the N64-GC was really that better the it was in the NES-SNES years. Maybe it was a little bit better, but considering the price you pay for that marginal improvement is the total lack of 3rd party support that's a really serious sacrifice to make.
Then we have the Wii which is the worst of both worlds because not only does it lack 3rd party support, but the 1st party offerings aren't really so great either (I'm talking Wii Sports, Wii Music, Metroid Other M, etc). There was some great 1st party titles sure, but there was also a lot of stinkers, and over all I wouldn't say it was Nintendo's best creative era. Far from it.
The only way Nintendo gets 3rd party support is when its dominant in the market, because then 3rd parties have no choice but to support it even if they don't want to. 3rd parties almost literally have to be FORCED to support Nintendo hardware. Unless Nintendo is a near monopoly its just not going to happen.