12px font also could become very small in the future, if typical computer displays end up having high dpi.
I guess a conforming browser should randomly sample computer displays before deciding how big 1px is.
Serious version: I don't think text like that should make it into a standard.
> If the pixel density of the output device is very different from that of a typical computer display, the user agent should rescale pixel values.
So actually 12px font should look about the same on all output devices, regardless of their physical DPI. But I agree that 12px is rather small for copy text.