I find it hard to believe that the designers of Epcot didn't know that their attractions would need periodic refreshing. I would be shocked if they didn't even have a chart projecting what the refresh cycle timeline would be and what parts would need to be changed as they aged and what the projected costs would be. I sure would want to know these things before greenlighting them.
The difference is that MGMT at that time understood that its part of the cost of doing business. Just like a local amusement park knows that they need to do a major ride every few years and do small attractions in the off years.
If you stop investing, people stop coming.
The problem became that the new MGMT, (starting with later Eisner and continuing with Bob Igor) didn't want to do the investment because they just wanted to keep using WDW as the Disney ATM machine. If you have to put back a $20 for every $100 you take out, your not maximizing your withdrawals. When the attendance started to dip, they created the festivals to get people to keep coming. Painting over the rotten wood that was growing. It wasn't until the festivals weren't cutting it anymore, did they realize that they need to put back into the ATM some of those twenties.
Compounding the problem is that the type of park that the Imagineers created as Epcot, demanded periodic updating. Magic Kingdom, not so much. Mainly just maintenance and capacity increases.
I would say that the studios is similar to Epcot, while AK is more like MK.
If you look at what they are putting into IPcot, you can see that its attractions with staying power so that they don't have to replace or highly rework them periodically. I would argue that they have done the same thing at the Studios, but still have some more to do.