Here's one thing I don't get:
Sure, you drive your M3 on blizzaks in the winter. But guess what - the blizzaks 100% kill all performance attributes of your car, including "emotional" steering feel. And I'm not just talking about the WS series either - their LM series is just so ridiculously soft. I know - I ran on them last season. Squealed taking a corner at 30mph.
Having Xdrive allows people in climates that experience a lot of snow to run true performance winter tires that have less snow traction, but much stiffer sidewalls and more grip in the dry. This directly correlates with better steering feel and higher performance.