Excellent point. And indeed, sometimes it is.
For instance, after practical birth control methods became available sexual activity outside of marriage became permissible. Maybe not within those organizations who have a dogma unaffected by science, but certainly within the larger population.
And the acceptance of homosexuality has at least in part been driven by knowledge that homosexuals aren't drooling to get into the pants of every male and his sons and that it must have at least some genetic component. Again, some organizations are immune to new knowledge.
Arf