Reading these kind of posts remind me of the old poem about several sightless men describing an elephant... by touching the elephant in one small area.
The descriptions are accurate, but ONLY FROM THE UNIQUE PERSPECTIVE of a small amount of observation.
We all see the posts that say, "The parks were not full at all during that week" followed by "The parks were PACKED all week".
Its because some folks experienced one park or TIMING of their adventure, and others were not as "synced" with the throngs.
I can tell you from several trips to WDW in the winter...
You can get LOTS OF VARIANCES in temperature!
Nobody can tell you that it WILL be "X degrees" at night or "Y degrees" in the mornings in December.
We have had MANY days when shorts and tees were perfect, nearly all day.
We have also had many days (especially early EMH) where a thick coat, zip-on gym warm-ups and earmuffs or stocking caps were a welcome outfit.
At night, I've spent a couple of evenings viewing IllumiNations in "gale-force winds" (well almost) and lower 40's... in the Florida humidity, THAT'S COLD.
(They don't even fire off all the perimeter fireworks when there are strong winds.)
On those kind of nights, we'll stop by the lockers, go into the restrooms, and slip on some thin thermal underwear... that'll keep you toasty!
So, yes, a Florida winter getaway is warmer than it generally is in the upper USA, but I've even been to WDW when it freezes low enough that WDW landscaping had to replace many of the outdoor plantings throughout the resort due to frost-damage.
Take the shorts, you'll need 'em, most-likely...
but when I go to WDW, I don't want to "stay indoors" when the cold winds howl... so we pack for the other extreme as well.
Its cheap "
trip insurance".