The “vocal parts of the community” were not against the UI change. For the most part, being the ones who were charged with putting in effort to make this improvement for free, they were pointing out the significant technical challenges it involved, and they couldn’t find someone to volunteer their own personal time for free to take on this challenge.
As Gnome has made massive strides towards simplifying its codebase, these changes become far more achievable and reasonable (click through to the developer changes page and you will see GTK4 has deprecated something like 20 possible file picker classes, in favor of 3, which provide equivalent functionality).
Of course, the same people who complain but are unwilling to either put effort or money towards fixing these supposedly deal breaking problems, have also spent the last 2 years complaining about the code and architecture cleanup effort Gnome devs have made to make it possible to fix those problems.