I think some of these characters are "reborn" as new characters. They get tired of the role they create, so they come up with a new one. Examples like Sleeper, Tiernan, etc. I don't think those guys got religion and just up and left. I think they had taken their characters as far as they could and got bored. So they reinvented themselves. You have to start with a new name to do it right. As I recall, Sleeper tried and in-game change from ultra Ayn Rand to gentle liberal and no one bought it. So he had to get "born again".
Hey man, this is America, if you don't like what you've become, change it.