Totally agree as well! I thought it was bad years ago when an occasional store was open on Thanksgiving Day...and then as you say, more and more have been doing so since.
I refuse to do any kind of shopping on Thanksgiving or Christmas. I do everything I can to have what I need (for baking, cooking, etc.) beforehand. And if I happen forget something (usually really minor anyhow), well then I figure that's too bad, I still won't go out and get it on the holiday itself.