I think in actuality what really gave hold to the "kiddie" notion was the decision to not use CDs with the N64.
Up until then, Nintendo made cartoony/whimsical games primarily, but it was never really a big deal because you had all genres and all different styles of games.
That stripped Nintendo of their wider content backing and really narrowed their library offerings.
If that hadn't happened, the N64 could've had games like Resident Evil, Metal Gear Solid, Final Fantasy VII, Silent Hill, etc.
In that case, I don't think the "kiddie stigma" would've stuck to the N64, especially combined with GoldenEye/Turok/etc.
But obviously history didn't work out that way. In a lot of ways, I think Nintendo is still paying for that one decision. It's never ever been the same for them with third parties since then.
I think if Iwata was in charge then, the decision would've been different. They would've kept the cartridge slot on the N64 but sat down with at least the Japanese 3rd parties and listen to their concerns and come up with a compromise (most likely a combo cart/CD system, like the Saturn, so both EAD and third parties would've been happy).
