In this case they closed the bug because a competing browser launched with the "bug fix" as one of its most touted features, and Mozilla spent several years rearchitecting Firefox in order to support the requested feature. This is a triumph.
That's not how I would describe it and not how it was described at that time. It was deemed necessary to discontinue legacy extensions to improve the browser.
Well, I could be wrong, but as I understand it, the particular way in which the browser was improved is that, now, browser and extension components can be sandboxed, which is what the bug was asking for?
