I actually enjoy this, but I'm a female. I don't know exactly why guys like it, but I think it's so there's a bit of assurance that you are enjoying pleasing them. It makes the moment a little more intimate and less cheap, as well. This is per a guy that enjoyed me looking up at him during oral. I'm sure he can't speak for other guys and I can't say that's how he REALLY feels, but hopefully that helps.