I'd hazard a guess that contraception was banned, originally, to ensure that the world population of Catholics increased rather than declined.
What I find unacceptable is that this is a rule made by men who are, professedly, celibate. If the church ever relaxes enough to allow its priests to marry I think the ban might be lifted. Not that it makes much difference in the Western world. Even in the most Catholic countries you don't find many large families these days.
Remember what Dave Allen said about the Rhythm Method? There's a little man with a bongo drum sitting in the corner of the room....................
