I know that not a lot of users disable JavaScript and so it is not an imminent worry for developers to support such users. However, having every special page render after 3 seconds or more because developers did not worry about the first paint render is unsatisfying, and it is completely unacceptable to have even a basic search page load and render via JavaScript-only.
I can only hope that developers would consider making this a form that is available on first paint, working and fully functional without any JavaScript loaded. If that is not on plan for developers before the (eventual) deploying of this form for all users, then frankly this should be rejected (as it is a clear regression from previous state, where you could use the advanced search form without JavaScript and without waiting for OOUI/other JavaScript to load).
Wikipedia interface already seems really inaccessible and unresponsive because of stuff like new RC Filters, RevisionSlider and the like, one must dread the day when article text will be loaded entirely via JavaScript too.