The customization element was nice, but I feel like most of these issues will be addressed by future developments.
With everyone using close to the same API, we have to move backward a bit, but one browser implementing a feature like file access means developers going to other browsers and saying "Why can't I do the same thing from the other guy?"
While this somewhat exists already, it will be much louder if they aren't entirely different plugin architectures and used as a developer excuse.
Firefox implemented file system access for extensions long before Chrome existed. They're just taking it away now.
If Mozilla wanted to go the standardized API route, they could have done that initially instead of introducing the Add-on SDK (Jetpack). IMO, that would have made more sense.
And if they wanted to, Mozilla could still allow XUL/XPCOM add-ons to coexist with WebExtensions add-ons until Firefox itself stops using XUL/XPCOM (which will most likely happen when Servo is ready for prime time). And by that time, maybe they could standardize js-ctypes as part of WebExtensions, which would address the middle 3 issues on my list.
With everyone using close to the same API, we have to move backward a bit, but one browser implementing a feature like file access means developers going to other browsers and saying "Why can't I do the same thing from the other guy?"
While this somewhat exists already, it will be much louder if they aren't entirely different plugin architectures and used as a developer excuse.