Not being revolutionary doesn't mean that these franchises have regressed. You can still make newer games that don't reinvent the wheel.
But even then Kirby and the Forgotten Land is the first fully-fledged, bigger scope 3D entry that isn't a smaller scaled nor a spin-off like Air Ride, Blowout Blast nor Battle Royale.
Then again what was the revolutionary game in the Kirby franchise before? Maybe Superstar? It was two decades ago and while it was a great 16-bits platformer it didn't revolutionise the genre. Return to Dreamland? It was the first major home console game since Kirby 64 but yet again it improved upon Superstar's formula while adding its own flair but nothing that was groundbreaking for the platformer genre.
I'd even argue that the only revolutionary thing about Donkey Kong Country was the pre-rendered Silicon Graphics 3D but aside from that it only has built upon the Mario Bros series. Maybe the heavier emphasis on collectathon compared to other platformers of its time may be an innovation but then again I think Super Mario 64 and later Banjo & Kazooie did it much better.
I would agree about Mario Bros as a whole but I'd argue that the most revolutionary game was the very first Super Mario Bros game for platformers in general and that each subsequent game has built upon it. Wonders still feels much more original and unique, almost like Mario World was back then compared to every other game since (not counting the Land games).