With so much negative response, it's as if nobody had to adjust a rangefinder for proper focusing. I wish my zeiss sonnar had an option like this for focus shift at different apertures.

You don't have to use it.

But some people use AF cameras. Some people use them with 3rd party lenses. Because the communication is digital, a number of older sigma lenses don't work on newer bodies and have issues.

So, considering that a camera becomes a complex system of the lens computer talking to a camera computer, it only makes sense to update the lens computer.

I love manual focus camera to death, but in normal light my AF SLRs focused faster and more accurately than any MF camera. And they do it off center as well. And they also track moving objects.