F-Zero is because Miyamoto couldn’t figure out what to do when Mario Kart 8 specifically took on the role of F-Zero with anti-gravity and additions from 200 cc to 8. F-Zero needs a reboot / trick to separate from Mario Kart 8.
Star Fox has long been marked by the derailment of the Star Fox Adventures franchise onwards. Nintendo tried to remake Star Fox 64 and restart Star Fox 64 only to fail to revive the series (the latter only failed because the Wii U and hardcore players refuse to leave comfort zones). Ubisoft’s use of Star Fox could do nothing. Star Fox is practically dead. Perhaps in 30 years Nintendo will try to restart the series again (Nintendo will only re-launch Star Fox 1, 2 and 64 over and over again).
Kid Icarus is mainly because no one is available and if anyone was available, no one made a successful pitch for a new Kid Icarus game. Sakurai has temporarily revived the KI franchise, but he doesn’t want to return to this franchise. Uprising had good sales, but it had strong reviews about the controls and Nintendo may feel that relaunching Uprising on a newer platform with better controls and better multiplayer balance will not be the answer to revive interest in Kid Icarus.
All other smaller IPs are IPs that just met expectations or fell short. Some of Nintendo’s new IPs from the 3DS era are lacking in action for Switch. Mallo and Pushmo are not seen since the Wii U / 3DS. Sakura Samurai has not had a new game since 3DS. There are several other examples.
If nobody buys these smaller titles, Nintendo has no choice but to make the Mario, Mario Kart, Zelda and Smash Bros. games. (upon receipt of occasional Pokémon games from The Pokémon Company). Yes, that means buying games you don’t want, like Paper Mario: Origami King and Star Fox Zero (Wii U).
By not buying smaller games and games that change the formula or have non-traditional controls, you see Nintendo in a third-party production role that they are now playing (after all, people have always wanted Nintendo to be outsourced and now we are seeing them in a third party production frenzy with few games outside of Nintendo’s top AAA).