I don't really think it's an option, they have to. The sheer number of attractions pretty much requires this. I know they don't do it this way, but imagine if they were to completely refurbish 2 or 3 rides per year, every year. With how many attractions they have, that would mean one would go many, many years before its' turn came up. So between simple repeated use, changing technology, changing guest desires, etc....the phrase "change is constant" applies. I'm as big of a WDW "apologist" as you'll see here, and even I agree there are still rides that need updating/refurb. Buzz for one example...I still thoroughly enjoy it, but it's outdated and doesn't work well.