Re: Long overdue
You can easily fix that in Firefox. Type about:config into the url bar, and copy-paste browser.backspace_action into the search field. Set the value to 2 and you're good!
I agree, it was a terrible "feature." Mozilla lets the user decide; Google decides for you.
There are tons of examples when Google could have left things up to the user, but opted for a "one size fits all" solution instead... like when they removed tablet mode (unified button/notification bar at the bottom, which conserves vertical space but requires more width, so it works best with devices held in landscape modes, as most tablets are but phones are not) from Android (in JB) in favor of making tablets behave like large phones (separate button and notification bars, bottom and top; it uses more vertical space but works well when horizontal space is limited, so it works best on devices held in portrait orientation, as most phones are but tablets are not), with the excuse being that people could become confused if they didn't find the buttons where they expected when switching from a phone to a tablet.
It's a specious argument, as when my tablet mode was removed for the JB upgrade, I could see that the notification bar was now on top, and that the main action buttons were now centered on the bottom instead of on the left. There was no confusion; I'm not a sphex.
Even if it was not possible to convince Google of how silly the "confusion" argument really is, it would have been really simple to have a tablet default to "big phone" mode and allow users to select the tablet mode, but that's not how Google rolls.
Another example from Android was when they decided that the URL bar will self-hide in Chrome. On a phone, the URL bar takes up valuable screen space, so they decided it was better to make it hide itself (even though disappearing UI elements has long been on the "bad practice" list). Users who preferred the utility of always having the location and controls on the screen, especially tablet users who have more screen space to work with, would simply have to live with it, as Google had decided how it was going to be. No user preference... just Google's way or the highway.