It is incredibly tragic what happened and I am beyond saddened by the loss of life. WalpoleJoe is correct. Even with all of our advancements in technology and science, we are just dust on the wind in the grand scheme of things.
The original question was "why were they operating?". I had read that the facility had recently switched to operating 24/7 in an effort to boost production ahead of the holidays. I imagine like most businesses, this one had a quota it was driven to achieve, and despite the warnings, perhaps many felt it was worth the risk to make quota. Or perhaps the building didn't have a storm shelter. Maybe "it can't happen to me" syndrome was present. Who knows at this point?
Admittedly, I have a growing frustration with what the holidays have come to represent in our society which was the impetus for the "American Greed" comment. I'm sorry if you are offended. I am frustrated that we as a society now think that the holiday season is now about wealth, objects, and presents. If we as a society would remember what the holidays were originally meant to be about; love, family, and remembrance of whichever religious deity we follow, perhaps the tragedy could have been avoided (at least at the facility).
Our opinions on this tragedy or of each other won't change what happens. All we can do know is pray that those suffering are comforted. If you believe in God, the bible tells us that he is a God of comfort. So pray that the families and friends of those lost will be comforted through their suffering.
I hope that you all have a lovely holiday season and find time to unwind and be in the presence of loved ones and friends. I also hope that we get a blizzard some time soon.