Yeah but back when he produced the SNES and 64 games he was still a genius and hadn't yet lost his touch.
But that's beside my point. My point is he didn't "start meddling with the franchise during game X" because it's been his creation from the beginning of the franchise. There are a few times where the license was given out, but those games are even less noteworthy than Star Fox Zero.
Also, you're basically saying: "Hey, I don't like one of the recent games you produced, you're no longer a genius. Even though I do love several other of the games you produced recently."
Star Fox, as a franchise, has often been used as a vessel of showing off unique mechanics, it's kind of like Steel Diver in that way. Lylat Wars was an exceptional title, but is not the rule; no other game in the franchise shone even close to as bright as that one. The quality of Star Fox Zero is on par with the rest of the franchise. The only really fair argument I see is that outside of Lylat Wars, Miyamoto hasn't been that good with Star Fox games.
I describe myself as a little dose of toxic masculinity.