1. Why doesn't every single Mazda 6 owner (in even marginally snowy areas) switch to snow tires each winter?
I've found it's usually one of three reasons:
1. They have an AWD vehicle/winter rat that they choose to drive on the rough days.
2. They've never experienced driving on winter tires themselves, and therefore are oblivious to the HUGE traction and control advantage that winter tires offer, even over an AWD crossover with "all-season" tires.
3. They claim to "not have the storage space", winter tires are "too expensive", or any other cheap excuse to justify in their heads why not to get them.
Frankly, they're REQUIRED BY LAW in other countries, and I believe they should be here as well, no matter what vehicle you drive, but I digress...
2. Which ones do you recommend?
I also can vouch for the X-Ice Xi3. I had them on my previous 6 (a 2010), and they were fantastic in the snow! They offered immense grip and control in just about any type of snow, from slushy areas to deeper snow you find in untouched parking lots. I had them for 4 seasons, putting about 7-8K miles per season on them, and they've NEVER left me stuck or stranded. I also liked them because they were H-speed rated, and they handled well in the dry and warmer days as well. They never felt soft or squirmy, unlike other winter tires I've driven/owned.
I currently inherited a set of Bridgestone Blizzak WS80s when I bought a set of MSW wheels for my '18. And so far, so good. They're a couple seasons old, but have about 80% tread left on them. The few snowy/slushy/miserable driving days I've driven have been uneventful, giving traction and control as well as the Xi3's did, but I've found on the warmer and drier days, I don't feel as confident with them as the Xi3's when I wanted to have a little fun. Granted it's still early in the year, I'll see how they last throughout the winter...
I also recommend downsizing to 17" wheels for winter. The bi-annual swap is much easier (and less expensive if you can't do it yourself), and the tires themselves will be MUCH less expensive than 19" tires, so much that a set of cheaper wheels and new 17" tires may be less expensive than buying a set of 19" winter tires by themselves. It was in my case anyway...