People will find any reason to complain.
Yes, it's Thanksgiving in the US. Yes, I'm in the US. Yes, I'll be traveling to my mom's house for Thanksgiving (2 families, mine and my mom and step-dad and my sister who lives with them). I'm not freaking out. Why?
Because A) I'm glad it wasn't delayed further, like until December 10th or whatever the predictions were. B) I can take two days off of WoW - it's not going to kill me. I can get right back at it on Saturday or even wait until Monday.
The only case where I could see B not being palatable is if you're in a world-first-contending US guild. In that case, you would want to get to max ASAP to get raid-ready. But really, since raids don't open for several weeks, can't you take a day off for Thanksgiving and get right back to leveling that evening or the next day?
I'm just saying the criticisms are overblown.
And for those saying "but the devs! Think of the devs!" the devs will still get their days off that week. It releases on Monday, they'll have M-W to fix bugs, take a couple of days off, an extended weekend, and be back to fixing bugs the following week. It's not going to be the end of the world.
If Blizz had released in December the cries would have been about devs having to work around Christmas, which is far more important.