It's interesting that (some) people probably can't get worked up over the multitude of crimes these people are committing (tax evasion, e.g.) - it's only when child-abuse is involved that they become outraged. There's something simliar going on in a lot of conspiracy theories, maybe. E.G. 9-11 conspiracy theories - the alleged culprits are committing numerous crimes that aren't anywhere near as violent as deliberately planning an atrocity, but the atrocity idea galvanises people. I've always thought there was this weird thing with conspiracy theories where there IS a real darkness, a real conspiracy, but it's not the dramatic, TV/movie -esque conspiracy that the tinfoil people go in for.
(Saying all this I''m not denying that there are paedophile rings high up.)