in my eyes, the 6th gen was nintendo's true fall from grace and led them to becoming a different company.
the n64 stumbled (5th gen), and the cartridge format damaged 3rd party relations... but the n64 still got knock out titles, was innovative (analog stick, rumble), had good 3rd party support, and retained decent market share.
nintendo, at that time, still high off the success of the nes and snes, was a juggernaut and "the one to beat".
but the gamecube is where they truly tarded out and damaged themselves:
#1 - purple
#2 - a controller that clearly wont work with a number of genres
#3 - late to market AGAIN
#4 - no mario game at launch
#5 - miyamoto thought the gamecube would ABSOLUTELY CRUSH the ps2 in sales, and everyone who bought a ps2 would also buy his purple little dingleberry console too
#6 - proprietary disc that only held 1.5gb of data vs ps2's max. of 8.5gb (dual layer)... esp. a crazy decision when they lost so much 3rd party support with the n64 due to storage limitations (did you learn nothing, nintendo??!) (ps i know they did it primarily due to piracy concerns)
after the ps2 absolutely bitch slapped the gamecube in sales and coolness, nintendo basically abandoned trying to be the biggest and baddest, and retreated into a corner where they'd release budget hardware and largely focus on 1st party games.
of course, the wii was a huge success commercially, but it was also the most popular among old people and filthy causals, moving nintendo further away from that "biggest and baddest" image it cultivated from the nes-gcn era.
old nintendo is dead (maybe hibernating). wonder if we'll ever get it back.