Maybe we don't want the children to be "more accepting, more tolerant" or whatever, of sinful behavior. We don't condemn or judge people, but we do condemn behavior, and we cannot "tolerate" it, because we know it leads to condemnation by God. We don't want the children to be drawn into the net of sin. That is really what this is all about. Flaunting one's sin is not a good thing, and exposing children to it is also very bad.