I think they stayed on version 10.x for so long (mostly under Steve) because it was a subtle reminder that his work at NeXT lived on at Apple. There were also rumors that they quickly bumped the classic Mac OS to from 8 to 9 to justify landing on 10 so that they could use the 'X' for 10 when they launched the new OS.
As for why the jump to 11 now?
One, Steve is no longer there to insist on staying with X (they may never have replaced OS X with MacOS).
Two, why not? Being the first version to support their custom silicon is a pretty big moment and worthy of incrementing the major version; although, I agree it also would have made sense to do so for the PPC -> Intel transition or the rename of OS X to Mac OS or even the Catalina release since it separated the system files.
Personally, I was more bothered by the rename to Mac OS than the version bump.
I still have a T-Shirt I got at the 1 Infinite Loop corporate store that says "The Joys of OS X". They can rename the OS, but I'm keeping the shirt.
As for why the jump to 11 now?
One, Steve is no longer there to insist on staying with X (they may never have replaced OS X with MacOS).
Two, why not? Being the first version to support their custom silicon is a pretty big moment and worthy of incrementing the major version; although, I agree it also would have made sense to do so for the PPC -> Intel transition or the rename of OS X to Mac OS or even the Catalina release since it separated the system files.
Personally, I was more bothered by the rename to Mac OS than the version bump.
I still have a T-Shirt I got at the 1 Infinite Loop corporate store that says "The Joys of OS X". They can rename the OS, but I'm keeping the shirt.