I'd love this feature. I used it all the time in the old Firefox days.
Middle clicking is harder on laptops and double-clicking uses only the mouse.
I know some might consider it bloat ("Get an extension!"), but I think laptop users would appreciate these features built in.
I'd actually like this "change" browser wide: middle-click-on-a-desktop-mouse should be activated by double-clicking with any mouse. Like opening links in the background!