Why does it matter? Resolution-independence means things will display right on whatever pitch, and ISO or ANSI size pages can be zoomed to fit. Even if you did have, say, an A6 tablet, and wanted to display an A4 document on it, you'd have no room for toolbar, page-selection scrollbar, etc. I don't really see any gains to that sort of hardware standard switching; whatever resources would be expended in agitating for such change might be better applied agitating for resolution-independence, or better, fixing non-resolution independent (free/open) software.