Cold tolerance seems like a very individual thing. I've been up and down the scale a few times in terms of my weight, condition and speed. It doesn't seem to have made much difference to my comfort levels in the cold. I think the coldest run I've done in regular shorts/shirt/shoes was exactly freezing. Even then I wore a thin beanie and gloves. Without those, I would certainly have been quite uncomfortable and might have been at risk for worse. Hypothermia is a real thing. I've seen it, and don't want to experience it.

I guess it would be nice if I could run wearing less, but I honestly don't think it would be safe for me. Your mileage obviously does vary. ;) As it is, I have winter shirts, undershirts, and socks that are all different brands, and I am keenly aware of which ones are better at which temperatures. There's a bit of an art to wearing exactly the right level of gear for the conditions, and I've simply had to become good at it.