The user interface is just minor part of the browser.
Mozilla's mission is to "free the web". Something like that can't be done with slightly sleeker UI on top of monopolistic rendering engine. You need to have an influence on all levels.
> as MS recently found out
I've read it this week in some interview with the FF developers that ever since MS gave up on homegrown Edge engine and adopted Chromium/Blink their voice on the standards committee is weak and lacks clout.
No wonder. It's google who keeps strict control over chromium/blink. MS can discuss, propose, even send PRs, but it's google who will decide what gets in and what doesn't.
> They had no SERIOUS attempt. Well until now at least. They did some half-assed with pocket and now VPN-reselling, but never touched real business.
Well yeah. But it just sounds a bit simplistic to say "just earn that $500 million profits somewhere so you can sponsor your side project Firefox".