OP here: I'm curious, do anyone know if the VLookup defaults make sense in any kind of way? I was first shocked when I realized this behaviour of VLookup, but then I was thinking that there was perhaps a good (although unclear) reason for it?
Yes, they could have made the argument required, and have their file converter add it, but users typed in formulas from magazines at the time, so that wouldn’t have worked there, unless they added UI for it.