Yup, been there, had that weather. Was there in 2010..it was brutal!!! I've had almost as cold weather other years as well!!! There has never been a Dec that I have gone into a pool. Yes, the pools are heated..but you have to get out of that pool eventually!!! The air is cold. 50 in central Florida is chilly.
The thing to remember....usually the week after Thanksgiving is late this year. There is usually a week in between Thanksgiving and that first full week of Dec. So a lot of people have found that week to be wonderful. And it was. But this year, the first week in Dec is immediately following Thanksgiving. It is a very desirable time for DVC owners...many go down this first week. Then, add to that the PopWarner kids arriving that week. I have been to WDW every year since '03, in early Dec. And it has been wonderful. And I usually don't have much trouble booking my stay at BWV, but this year? Didn't happen. I missed my 11 month booking window by a week....wasn't able to book at BWV!! There will be a lot of people heading down this particular week.
The holidays are wonderful at WDW. I love going at this time of year. BUT...the weather can be wonderful, or it can be downright cold!! I've been there when I could wear a tee shirt and shorts every day, and just put on a sweatshirt at night. BUT...I've been there when it was too cold to wear tee shirts and shorts at all...other than for about an hour midday, in the sun!! Layers are the order of the day in Florida in Dec.