That's kind of what reputation is like. Once you've lost it, its gone.
Mozilla were warned when they switched to this chrome-like release schedule that this would happen, but their focus was on trying to get speed improvements out quickly to avoid being far behind in the benchmarks. Sustaining their existing strong points wasn't a consideration.
My experience is that the ecosystem of extensions has shrunk. Some I used to use were abandoned; now when I search for addons I often find something I could have used, if it hadn't stopped working 5 versions ago. Developers who in the past could successfully maintain an extension with a little effort every year or so, got driven away from the community.
It's true, those still running break less with new versions (firebug seems to update every time I start the browser to keep up). It's happened by selection within the shrinking pool.