Tho I agree, playing devil's advocate I'd have to point out they are trying to remove the market for the kiddie porn. Remove the market and the producers will dramatically drop off. Only a minor percentage are paying for it, but there are also a lot more that are funding the producers/distributors indirectly with banner impressions and clicks, and with zip files of KP with botnet/spyware sprinkled in.
Why not? It's been working so well to shut down the drug trade.