I wanted to chime in as a Cast Member. As a Cast Member, I truly enjoy working holidays. The reason I became a Cast Member is because I enjoy creating memories for other families, much like others created for mine when I was younger. For many families, the Holidays are the only time they can get way from work and school to enjoy each other's company in the parks. It's my absolute pleasure to be a part of that and add a little bit of magic to their time together. We work so that others can play.
As for my own family, we celebrate the holidays on our day off before/after the "actual" date - as a Holiday is not necessarily a date on a calendar, but rather whatever day we decide to make it.
I hope that the Disney Parks never close on Holidays (and I don't think they will), because they were designed by Walt to be places that families can come together to enjoy each other's company, as a family unit. Holidays are the best opportunities for modern families to disconnect and do exactly that.
*Keep in mind the opinions expressed by me do not reflect the opinions of The Walt Disney Company nor it's affiliates.*