Are there statistics on child pornography over time? Is it spiralling out of control? Is it diminishing to zero? It would be easier to live with the pearl clutchers if there was lots of good evidence to show that owning illegal JPEGs causes either JPEG production or abuse offender rates to increase, or that decreasing JPEGs correlated with a downturn in offending.
It also might be ok to ban stuff because it feels like the right thing to do, but it’s not an amazingly solid argument.