I think that the "no sacred cow" "let's blow up what we have" brainstorming method of doing things also has a serious downside. I fear such sessions blind people to the strength of what you already have, and allows some truly mediocre changes to gain momentum. Stitch's Great Escape, which nobody seems to like, may have arisen from this. It's a bad attraction that gained momentum somewhere without true thought going into a truly good alternative, or even keeping the old attraction until something good could be developed.
The new and terrible narration for the Tomorrowland Transit Authority is a bland atrocity that appears to have been born from a desire to point out the gift shops while tearing the heart out from a cleverly written attraction. The old narration, with great voices and a tranforming way of making you feel as if you really were in a spaceport somewhere, was dumped because of some stupidity somewhere. Was it a short-sighted brainstorming decision that ripped out the old narration?
And Judi Dench's Spacehsip Earth narration sounds more like an old schoolmarm than the timeless traveller of history that Jeremy Irons' voice brought. I like Judi, and I like the update, but Jeremy's voice was better for that attraction.
All changes, yes, but the positive properties of a valuable established component appear to get lost because momentum leads to something that everyone wrongly thought could have been so much better. Perhaps I'm conservative by nature, but I instantly assess the old and discardable thing for its positives before jumping onto some new bandwagon that leads to lesser results. New Coke is a prime example. Unfortunately, once that momentum get's going, people are less likely to speak up and say, "Is this really any good?" Sometimes that emperor just doesn't have any new clothes, and the old outfits are good and sitting back in the closet.
Blowing up, at times, can lead to this result, in my opinion. For me, blow it up by first asking, "What are the true positives of Epcot?" Search for those first, then consider blowing it up after your positives are well considered. Otherwise, the blow up may gain momentum and the positives are forgotten. Who wouldn't get excited about transforming Epcot into something completely different? Once that energy starts flowing, it's fun. Meanwhile, the beauty of the current Epcot is ignored, looking old and stale compared to that transforming idea that everyone is abuzz with. You walk around and think about the changes, becoming blind to the greatness of what you already have. Therein lies a true dowside, and some care must be focussed to keep such obviously bad changes from being made.