Re: Such is life. Have a look around - it's a constant race of arms.
Oh, come on. While I am just as annoyed as anyone else at losing my personal faves - NoScript in my case - at least temporarily, this analogy is pretty darn leaky.
If you had a leaded gasoline car, you'd be out of luck, unless you did whatever you need to do to keep them running on modern gas.
If you had bought lots of cassette tapes, you'd not have them working on any recent equipment.
If your light fixtures for some reason insists on incandescents...
And, how many times have we seen people complaining that Windows is a mess due to its support for outdated technologies? How many people have - justifiably - skewered IE for leaving all sorts of crud enabled?
FF has put in a lot of effort rewriting their core, it's time that we get some payoff.
There's always a fine point between gratuitous changes and ones that make sense going forward. Python 2 vs 3 is a case in point - the changes to 3 were important clean ups in a language that takes clarity and consistency very seriously. To the best of their ability portability was facilitated and stuff back-ported to 2.7. It's not super difficult to write code that runs on 2 and 3*. But, yeah, it broke code. I'm still on 2.7 myself, but I disagree that the whole idea was an unplanned clusterf**** and will eventually move to 3.
Uncomfortable and inconvenient? Yes. Unjustified? No. Sometimes you need to change things and I respect that, as long as you aware of the costs to your users.
Browsers are too central to current computer security to take risks from keeping huge chunks of legacy code, including extensions that may essentially be un-maintained.
I'll give the benefit of the doubt to Mozilla, one of the better software projects around IMHO, that they've done a good job, weighed the alternatives and had reasons for doing this. Then I'll wait for NoScript before upgrading. If they've really screwed the pooch I'll switch to Vivaldi.
What I won't do is compare my ($$$) car to my (free) browser ;-)
* which is not to say that what makes sense in a development framework - where the complexity of compatibility is the developer's choice and is limited to their app - is the right thing to do on a browser.