On another note given that Wikipedia's content is in the open, maybe this new UI could be hosted at another domain e.g. pickypedia.org or itchypedia.org or something else funny instead of being a Chrome plugin.
Chrome plugins add more unwelcome startup bloat to the web browser, and while they are super useful to fix the UI issues of commercial, copyrighted websites, Wikipedia can totally legally be replicated at another domain.
You'd still need the old wikipedia to edit any articles and you'd still need a browser extension to redirect regular wikipedia links to your favorite frontend.
Also just like with open source projects, just because you are allowed to fork does not mean that you should as you could end up hurting the original project by e.g. confusing users.
Chrome plugins add more unwelcome startup bloat to the web browser, and while they are super useful to fix the UI issues of commercial, copyrighted websites, Wikipedia can totally legally be replicated at another domain.