it does sound horrible. but i think i see the rationale. it sounds like it's about cleanliness. menstruation is sloppy, infections can be sloppy etc. if infections are unpleasant and menstruation "unlcean" (bear with me in a culturally relativist kind of way for a sec), then dry must be sanitary, clean etc. And maybe it comes back to the whole fear of womens' pleasure too. i know friction can't be good for a man, but the moistness itself is a consequence of female arousal (a protective response to anything entering the vagina. in arousa, it predicts subsequent entering and makes a pre-emptive strike). Girly arousal bad. evil. must smoke the demons out.
Hope you all figure that this isn't so much my opinion. i'm all for squelchy squechy mutual loveliness.