Reader should have an option to display more than 2 pages wide. MS Word has done this automatically for a decade; on my 30" monitor, if I set 75% zoom it shows 4 pages wide, showing 8 pages at once. 100% zoom fits 3 wide perfectly.
The fact that monitors have gone widescreen is all the more reason to not restrict the number wide to 2. And there's no advantage to the current system, since when you zoom out there's just wasted space beside each pair of pages.