Who is going to make all the web applications for firefox? I work for a small web developer(under 20 people). We use firefox to build the initial version of the website. webdeveloper, inspect element, gotta love them. But we do *not* upgrade our desktops willy nilly. We don't have any mandated corporate policy. It's just common sense not to upgrade at the whim of some external entity(mozilla, I'm looking at you), when we all have different projects all being worked on in parallel.
I might be personally working on 3 jobs at once. A coworker could also be working with me on one of my jobs, but then have others that I am not involved with. We won't upgrade until we have a lull in the work load. And that will *not* be right after a new release.
Yes, the linux kernel has a fast cycle. But even they have stable versions that they maintain. You can *not* go to a fast cycle without having long term stable branches. Whoever(single person or group) made that decsision(I'm sorry if this is abrasive(actually, no, I'm not)), was a moron.