I find it irritating because one of the core principles of this kind of technology, to me, is that it should serve the user, not the other way around. I expect to be able to run the earliest version of windows 10 and go out to all sorts of virus-laden websites if I decide to. It's one thing to automatically download updates and let the user apply them when ready, but to actually disable the browser until the user complies is just unacceptable for me. Hence why I disable it.
I do applaud firefox for supporting so much customization, as in this case. If I weren't able to disable this behavior I would have stopped using firefox immediately.