My take on it is to do with the social conditioning, similar to what Morv said. However, when you dig deeper, it isnt just diaper's which are taboo, it is almost any 'alternative' expression of being different which gets demonized. Has anyone ever heard of David Icke? A truely excellent author, talks about the Illuminati conspiracy, etc. Well, his take on social conditioning is so spot on. In order to control the sheep herd, you need very strict rules of what is considered:
Sane and Insane
Possible and Impossible
Moral and Immoral
If anyone goes against these social norms, then they are jumped upon by the rest of the sheep who are happy to be conditioned. We are all very unique people, every single human has a different take on life. Sometimes we find people with similar interests and desires, which just goes to show, with the diaper thing, how 'insane' it is. There are hundreds of users posting on this forum... I guess we should all be carted off to the nut house! Hmmmm, padded walls