There's no universe this doesn't negatively affect the UX of the OS for non-touch users. You can't simply support (or rather you can half-arse) new affordances without contorting the rest of the already well worn paths.
How do you think webapps work today? Is macOS UX actually well thought out to begin with? (no)
It's a nonissue when you look at the state of macOS attention to detail nowadays, regardless of which side of the fence you're on.
Windows did this seemingly by not caring that it's also a touch screen, so not everything in the system is touch-friendly. It's still fine for many situations.
I can actually see a possibility where this improves UI/UX a bit. One being the removal of some many hover-over UI elements, e.g., the (x) button on notifications do not display unless a mouse is hovering over the notification badge.
So, it may makes things a little easier for some GUI scripting. I can also see the UX improving for some disabilities, but I know that is merely coincidental rather than intentional.
But they have already done it. The updates are already in macOS and they have not negatively affected the UX.
Those changes are already in the latest macOS. So feel free to share your opinion on what we’ve already been using instead of speculating.
Most Windows laptops have had touch for a very long time now.
Does that mean you also believe the same to be true for mouse affordances ruining it for keyboard users and vice-versa? Or "touch" is special in this regard?
It already has, see the massive increase in UI padding in Tahoe and later. Windows and GNOME both sacrificed their UX to support touchscreen laptops years ago, Apple was one of the holdouts before that point.