It’s true that the regulations about sex and menstruation are designed to produce sex around the fertile period. But Judaism doesn’t have the Christian preference for virginity or for celibacy. Sex is for companionship, not only for procreation; women as well as men are expected to enjoy it; and this is right, proper, and according to God’s will.
If you understand the parable it is not that the goats are evil it is that they fail to do good.
Most of the imagery associated with goats and the devil is not from early Christianity, but from much later. Neopaganism came to identify the devil with Pan or Baphomet and depict him as goat headed.
I was thinking that it was merely a way two label two groups, but it seems to be related to similar things like the wheat and tares parable. And tares definitely have a negative connotation.
I hope this isn’t off-subject, but modern depictions of Satan have him looking somewhat goat-
like: horns, narrow face, GOATee :o, cloven hooves, etc. Is there some relation?