From what I read a few years back, and I'm not sure it's still applicable but I would guess that it is,
Disneyland in particular is propping up the entire Disney corporation. It's not that Disneyland itself is struggling, but as a corporate entity, Disney is. I imagine they feel they may be able to cut costs at Disneyland while maintaining high revenues, but time will tell.
But this decision strikes me as a direct punch to those who already tend to pay the most. I don't really mind losing that particular perk but it's a slap to replace it with something relatively worthless IMO. It also feels like a poor business move to "kill the golden goose," but I guess we'll see if this actually gets much blowback.