Here are two snaps. I didn't rotate them as the built-in pdf reader doesn't support rotation(yet), but the width (and thus letter size) is about right. I have no idea how you judged 3mm high characters on a N810. That would mean (huge) 1cm letters on a US letter sized paper.

You can clearly see the letters fitting between the 1mm lines (the sub/superscripts being less than 0.5mm). Reading this is NOT convenient, more resolution would NOT make it better from a practical standpoint (only more tempting to mess up your eyesight). There is only so much your eyes can resolve.