While it's not unusual for construction projects to have big impacts on the parks for a short time, or small impacts for a long time, this project is different in that it has big impacts that have lasted (and will continue to last) a very long time.
As a point of comparison, construction for DCA's big redo stretched from fall 2008 until summer 2012, but the major impacts in any given area were much smaller, mostly lasting somewhere between a few weeks and a few months. The walls were constantly shifting, minimizing the impacts at any one time. Individual projects were completed independently of one another (and quickly!) to ensure that an adequate number of facilities and circulation was left open at all times. It meant that many things had actually opened prior to the big splashy relaunch party, but it made the park a lot more tolerable while it was all going on. In some ways, it even built the anticipation of the finished product, as little bits and pieces of it were revealed over time.
The longest construction in a single location within the park was the World of Color installation and Little Mermaid construction, which started in early 2009 and opened in summer 2010 (though construction was mostly complete in early winter 2010) and winter 2011, respectively. There was a short stretch (about 6 weeks) when the area between the Mermaid building and WOC viewing area was closed completely for new pavement, but the area was mostly kept open with a corridor of walls for guests to pass through.
Additionally, only Golden Dreams, a sparsely-attended film attraction that showed to a couple dozen guests per hour, was "lost"
from this area during construction; there were no other facilities (attractions, merchandise, food, restrooms, meet & greets, etc.) displaced by it. While it was a relatively big construction site that impacted views and general ambiance, the impact to park operations was actually quite small during that period.
The biggest impact to park operations was the closure of the Sunshine Plaza for its transformation into Buena Vista Street, when guests entering the park were routed backstage behind Soarin' and guests exiting the park were dumped into Downtown Disney. Additional paths were added throughout the park (most notably, connecting a bug's land to Tower of Terror) to provide alternate circulation and access. Countless ODV kiosks were sprinkled around any quiet corner to make up for the lost merchandise capacity, and distribute crowds away from the construction. This period lasted from late August 2011 to early June 2012, well under a year, and intentionally chosen to cover the periods of the year with the lowest attendance. It was also scheduled to occur after WOC opened, to give guests a reason to deal with the headache of getting into the park (but not while it was brand new), since it was feared attendance would disappear if the entrance was closed before anything new opened. It was a heavy impact, but it was over fairly quickly, like ripping off a band-aid.
Now compare this to the current project a Epcot, where the wide-scale impacts of this project have been massive and long lasting. Walls went up around Innoventions East and the Fountain of Nations in September of 2019; it's now October of 2021, and there's no indication that area will be open to the public any time soon, or that Disney even knows what they're building there. Numerous facilities in that area have been removed with no replacement, in a park that lacks alternate options with available excess capacity, and park circulation has been severely impacted by the lack of access across Future World. Only a few weeks ago did Ratatouille and Harmonious open, as some sort of enticement to partly offset the dire state of the front half of the park.
This is all compounded by the fact that it's not even clear whether the final product will replace all of the lost uses that were in the (already partly-abandoned) buildings prior to the project starting. It was always clear that DCA's redo was going to be an unobjectionable improvement. At best, Epcot seems to be returning to its original form, but with fewer things to do than before. I'm sure the open spaces will have lovely landscaping, but is that really enough to justify all the trouble of years of construction? Is it even enough to justify the ticket price to enter the park once everything is complete?
It's not that a little discomfort isn't expected or allowable during construction. The problem is the size and duration of the impacts to the park, and the lack of meaningful mitigation to make the guest experience a little more bearable during that time.
If one of the best things to come of this overhaul project is the temporary convenience created by a detour, that's quite an indictment of the final product. It's only more convenient for a couple (unpopular) items, and the loss of access directly across (either north-south or east-west) more than offsets any benefits gained by this setup.
However, if there are going to be ongoing disruptions to the guest experience, these paths are a great example of the sort of temporary infrastructure that makes it more tolerable. They're not going to be around once the project is done, but they make the park a much more liveable place in the meantime. If only more of these paths could be provided throughout Future World, even if they're constantly changing and shifting every few weeks or months, then maybe these ongoing impacts wouldn't seem quite so bad.
Instead, we've got all the pain of ripping the band-aid of quickly, while still taking just as long as going one hair at a time.