I think in the case of mainline Mario, people were just taken off by the hiatus we been having since Odyssey and Wonder.
But that's actually not that uncommon if one takes a look at mainline games during the SNES, N64 and GameCube. It's just the Wii/DS and Wii U/3DS that spammed Mario a bit too much
AKM221 - 10 Years of Loud Chaos
I understand people want a brand new 3D Mario game, but if these two are finally getting new games after years of being neglected by their companies, I personally say it’s a fair trade off.