The lens is communicating with the camera body, and you might want to adjust for newer bodies supporting more things for instance.

I'm not aware of what exactly is changing, but I've already seen it happen with newer Sony bodies getting released, and an update going to Viltrox lenses to fully support thems.

On the camera and lens being separate...in an ideal world you could ask the camera to do absolutely everything. In practice that's a tough order for a single company.

The bright side is also that you can use a mildly older body while benefiting from a very flexible lens, or have different profiles for different lenses and not have the body care about which lens needs what.

I can't imagine Nikon be bothered to properly operate a software ecosystem TBH.