I grew up just outside of Sudbury in a small subdivision which was almost never plowed and, while this is going back a few years, not only did we have to walk to school, but they also shoved us outside when it was near blizzard conditions. You don't need to have special outerwear to survive the cold snap - you dress in a few layers plus snowpants and a jacket. Schools don't let the kids outside when it's cold - today was the first morning all week that they've been outside - and if you send them along with a sweater, they'll be fine once inside.
THAT said, I was one of the parents who chose to keep her kid at home on Monday and Tuesday. Monday was a mess and my car was stuck in the snow - there's no way we would have gotten out of the alley in my little sunfire. I work for myself at home, so keeping him home wasn't a big deal. Turns out, with less than 1/3 of the school there, there wasn't much to be missed. Honestly, I would have brought him in on Tuesday if they hadn't canceled the buses. I spoke with the principal and she expected even fewer students than Monday, so there wasn't going to be much to be missed again.