I totally agree with Anikin, that this is just another way a manufacture can turn out a product that can have lower tolerances. You shouldnt have to do this out of the box with a nice new lens, but I am sure there are those who really like to test their gear, would be really into this feature for test charts and so on.

I prefer manual focus all the way with a nice focusing screen or a contrasty rf patch, if I have to use an auto focus camera, I always set it to center spot and recompose, no matter how many af points there are, the cameras always seem to pick the wrong one when you need it most haha.

It is interesting to see though how camera and lens manufacturers are currently trying to differentiate their products, sigma has even renamed a new series of lenses, labeling them as Contemporary, Art, and Sports. I wonder what else is in store for the camera market now that it seems to be super saturated across the board for both professionals and amateur alike.