All operating systems have their issues and benefits, let's not pretend AmigaOS/MorphOS* haven't.
Linux distros have large installs due to the large amount of optional software that comes with them. If you're going to talk about things on a level playing field, then talk about the absolute most minimal installs of the operating systems, and then things suddenly change dramatically, don't they.
Re: Mozilla being bloated. Ok, so it takes longer to start up than most browsers. But Firebird not bloated? Has anyone checked the installation footprints of both? I have on win32... Mozilla comes out at 19MB, Firebird comes out at 17MB. Considering especially also Mozilla can currently do more than just be a browser.
* - ok, so I haven't used MorphOS, but I would place a large bet that at version 1.4 it isn't perfect.