IMO, commercialism moreso moved into the empty husk left after the Calvinists got to holidays, especially the puritanical sects that took root in the US. Specifically, I blame double-predestination: if you tell a bunch of people with free will that everyone is sorted into two groups, one going to heaven, one going to hell, and that the people going to heaven behave a certain way, it creates a much more oppressive, all-encompassing culture than traditional Christian "apologize and go to heaven because Jesus loves you" teachings. If your concern is not being judged negatively in the afterlife, you basically just need to follow some rules, try to be a generally good person, and you're generally free to do whatever else that isn't covered in the above categories. If you're concerned about demonstrating to others in your community that you are one of the God's chosen, who behave a certain way, that necessarily becomes universal factor in your life, which keeps escalating with time. This preoccupation with not being perceived as "having to much fun" so-to-say killed festivals.