I liked how I could feel each contour and crevice of the compacted snow. For me, the thin 1.2mm sole was just enough to protect me from thermal contact transfer down to about 0F/-20C, after which I would need to put on some smart wool socks.
Keep an eye for the Winter Challenge thread, starting in October. Many of us run barefoot at least part of the time in the winter. Everyone has different tolerances. I'm not much good with moisture below freezing, but I'm OK on drier surfaces down to about -20C, at least for shorter distances. Others can handle moisture (snow/slush/puddles) quite well below freezing. You might surprise yourself how low you can go if you allow time for adaptation.
For casual wear options, check around on old threads. This gets discussed once or twice a year, and the minimalist casual footwear market seems to still be evolving rapidly.