Then they replace their UI code so they do all of those things
Nope, different projects. Australis wasn't part of any of those.
and because you don't like it missing some features
More like, Mozilla deliberately killed some features because they thought we were too stupid to handle them, and when people asked them not to, they basically said "sod off, we don't care".
Would you rather have a browser you can still customize away from the defaults, or something like Firefox 2 or 3, where you have to sacrifice a lamb to change the UI substantially
Hm. I'm on Firefox 3.6 and it's a ton easier to customize than Australis. I prefer to have my stop and reload buttons between back/forward and the address bar. On 3.6 I just do it, on Australis I can't do it at all. Same deal with a bunch of other stuff. I guess I can't easily rearrange icons on the status bar, but then I can't do that with Australis either, can I?
presume that the only thing they need to do in order to get their way is spew more and more vitriol
It's more like: we've tried every other option and Mozilla just doesn't give a shit, so what's left to do but to bitch? If we shut up about it, they'll just assume we were complaining because stuff changed, rather than because we didn't like what it changed *to*.
All of that energy could have solved a real problem by now
"My browser pisses me off every time I use it" actually is a real problem for some of us. I groan every time I need to launch Australis to test some newly committed feature, there's no way in hell I could deal with that every single time I need to open a webpage -- and I'd have a hard time getting any other problems solved if I was that pissed off all the time.