The list of holiday things that have been removed, is a big deal though. My first Christmas trip was in 1998. Since then, this is what is no longer there
MK
Country Bear Holiday Show
Twas the Night Before Christmas Show
Seeing the Christmas Parade as the day parade more than a couple days before Christmas
Holiday Decor in Mickey & Minnie's Houses
Garlands across Main Street
I don't know how many random trees have been removed, I know Diamond Horseshoe and Liberty Tree Tavern used to have decorations, but I don't know if they still do those, or any other things I forgot.
Epcot
Lights of Winter
Gingerbread at American Adventure
Seeing Candlelight without effectively requiring a dinner package (friends from last year, said they only let 1 row of people from the non-dinner line in)
Studios
Train & Tree setup in front of the Theater
*Osborne Lights - going away
* unknown how the rest of the decor will change, I hope they keep the stars on Sunset
Animal Kingdom
Character Trees from Camp Minnie-Mickey
Jingle Parade
Elsewhere
The ornaments from the entrances to the golf courses
Gingerbread houses at each resort
Downtown Disney's tree (that tiny blue thing didn't last long)
I know the Contemporary's decor has changed quite a bit, I have a small picture of the metal trees they used to have in the lounge
I also have a picture of a fairly large tree at Riverside, but then the last time was a dinky little tree
Oh, on our honeymoon at French Quarter they had garlands on all the lamp posts
And this is before my time, but it probably is a loss for others the Glory and Pagentry of Christmas live nativity at the Marketplace which according to the boycott websites, ran for 17 years.
And just the awe of how much was put up in a 24 hour period. Now they stretch it out for weeks. The WL tree might go up in one night still, but so much doesn't.
Lots of people say "there's nothing better than WDW at Christmas," and at one point that was true, but is it still?