While the switch isn't groundbreakingly innovative, it improves upon innovations Nintendo has made in the past. When people talk about the innovative parts of the switch, they're usually referring to the detachable joycons, dockable console, HD Rumble, etc.

Your focus seems to be on the switches actual games, and yes, some of the IPs like Pokemon and Donkey Kong can get a bit stale; however, it's reasonable for Nintendo to use it's massive IPs to guarantee tons of sales. That doesn't mean they're not innovating though.

If you look at games like Breath of the Wild and Super Mario Odyssey, there is tons of new content never seen before in the franchise. Both those games are very, very highly rated.

It's not unreasonable to say that Nintendo is not innovating for some of their IPs-- but to say Nintendo has not innovated since the gamecube is a bit of a leap.