The utility of the long tail of Firefox plugins was what gave it its value. I've been using a hybrid of Pale Moon and Firefox since the last round of losing plugins and now don't see a reason to keep Firefox at all.
While I definitely see where you’re coming from, I certainly prefer building for better peformance as opposed to supporting everything forever. Analogous to Windows, supporting all the old things gave them a strong edge in their business, but they also paid a very hefty price on it (performance issues, security loopholes, BSODs to name a few).
In one sentence, the move to more aggressive multithreading and sandboxing. The old extension model conflicts with the boundaries that had to be established for both these things.
Part of the breakage is precisely due to the explicit intention to drop all the legacy APIs and the respective shims that have become too much of a burden to maintain over time.
One major technical change would be the deprecation plan of XUL/XBL (the toolkit used to build the interface, which could be freely accessed by addons) in favor of a wholly HTML future.
AFAIK, the old add-ons could interface with Firefox in any way they wanted; they had carte blanche. You can imagine the dependency hell and security risks; it's not desirable to duplicate that.
> You can imagine the dependency hell and security risks; it's not desirable to duplicate that.
I really disagree with the 'security risk' angle: it's my browser, and I've chosen to install the extension. That extension executes with my authority. Crippling what extensions can do because one doesn't trust me to run software on my machine is just crazy.
It's not crazy, it's what you do when you make software that's intended for lay users and is a big target for criminal activity. Us "power users" are not the people that are the primary concern.
That did used to be Firefox - Firefox became so popular because it strongly appealed to power users, who then evangelized it to friends and family.
Over the years, Mozilla has increasingly targeted the mass market. That's well and good, though I don't know how they can compete with being the default browser (Safari, IE, Edge, Chrome) or with massive advertising and heavy pushing on Google's homepage or in auto-installers like Chrome, no matter how good they make the browser. But what happens to power users now?
