I spent the first 30 years of my life in the UK and US letter paper always looked too squat when I encountered it at work. I've spent the past 11 years living in the US. I recently dug out some old papers on A4 and they looked weirdly elongated. It's surprising how strong the perceived weirdness of paper dimensions could be and and how easily it was changed. Seems like it's totally subjective and we could probably be comfortable reading in many proportions.