I think it's the "taking it way too far"-aspect of it, compared to a regular calendar[0], that makes it so creepy. It's the fedora and trenchcoat of calendars.
[0]Which my casual duckduckgoing indicates a filofax is.[1]
[1]On re-reading the above, I fear it might have sounded a little condescending, which was not my intention. I've just never heard of filofax before. In Denmark we just call those calendars or occasionally "Mayland", after a popular brand that makes those.</tangent>
