Nope I hadn't yet! Well one I asked specifically why their projects tend to cost so much more than Universal's. His response was that Disney spends WAY more time constantly modifying designs, second-guessing, taking things into meetings, etc. Universal basically says "we want this, make it happen" when Uni Creative comes up with something, and then they immediately push it out the door to get built. Much of this, in his opinion, is due to Uni's higher reliance on hit franchises that perhaps can't wait to be built 4+ years down the road, and also due to just a stronger desire to grow quickly. They sort of just take the first good design and run with it, and that results in much more streamlined design development costs.
Disney, meanwhile, questions everything - every component of the design is taken into some kind of meeting and debated, adding months or years of salaried design work. He talked about how cast member focus groups were brought in and asked "is this how you would use this, is this dispatch station set up well, etc." and then going back to revise entire designs based on their feedback, something Uni probably wouldn't do. And then many different proposals are looked at - they might build 10 elaborate models with slightly different color schemes and then just go with one of them. That kind of thing. It sounds like a lot of the expense IS spent due to Disney's obsession with detail, trying out several different lighting schemes for an obscure portion of a ride or picking out the exact style of faux-wood that would look best in an area.
And revisions, revisions, revisions: management comes in and says "the operations department doesn't like this, find a way to add more vehicles, expand the loading area," merchandise comes in and says they want more room for the gift shop, cast member managers say they want a bigger breakroom, so the ride footprint gets reduced, every time shuffling square-footage around and redesigning major components of the attraction. Just tons and tons of second-guessing and modifying it sounds like Uni doesn't do. He said this somewhat defensively, as if all this careful consideration of design leads to a stronger design product and "the Disney difference" (and maybe it does). But at some point you have to wonder the trade-off, at what point the pursuit of perfection becomes inefficient and wasteful, and as NoChesterHester said, whether all that design effort would be better spent pushing things out the door and getting stuff built at a cheaper price to try and quickly fix WDW's problems. I know personally, I would prefer a New Fantasyland that is 80% as pretty as the current one, with a restored Imagination pavilion to match, but maybe that's just me.