Without question the castle is Cinderella's! Listen to what the fairy godmother says when asked in the old show about decorating the castle. She says they should ask Cinderella because "after all she lives here". Fairy godmother doesn't say that Cinderella lives in the back!
It is her castle being lit up, not the stage. We go every year during the holiday period and the previous show made sense. Cinderella said what she wanted and the fairy godmother granted her wish. Classic Disney.
Completely changing what was a MK holiday tradition is much more like sticking Frozen in my face than just seeing the merchandise everywhere. You can overlook clothes and toys but if you wanted to be there to see the castle lit this year you couldn't escape the Frozen part. How much more "in your face" can it get next to sticking Elsa and Ana on the sleigh with Santa...or worse, next to Mickey and Minnie on their float?
We've been to
MNSSHP 5 times and that show has nothing to do with decorating the castle for a holiday. It's just a Halloween show that begins and ends and the castle returns to normal when it's over (the usual colored lighting). Totally different.
Can't argue whose castle it is at WDW...heck, they named it! Back and front, left side and right side, 1st floor and second, my daughter is right when she says it's Cinderella's turf!