It doesn't really cost that much to apply a holiday overlay if you're doing it every single year, though. I wouldn't say it's being "cheap" if there's no need for it. Deferring maintenance, yeah, that's being cheap. But not applying holiday overlays because only a select few (the comparably small percentage of locals WDW attracts) would appreciate it as much as in Disneyland is just budgeting appropriately. Why take the time to do something that's unnecessary?
EDIT: Not to mention, the Disneyland holiday overlays (HMH and Ghost Galaxy) aren't there because they're just some super cool thing to do. Their purpose is to bring out more guests during the typically slow Halloween period. At the end of the day it's still a business move. WDW doesn't have a slow period, err go, no need for holiday overlays…just another business move.