Ones and zeroes in my own property are not influencing anything in the "real world". If I use them and they are a virus and damage computer systems, that is a crime. If I made the virus just to learn about hacking, that should be perfectly fine.
Childrens' safety is not a digital thing in a computer, and AFAIK nothing suggests childrens' safety is more at risk right now than from other forms of violence that seem to be perfectly tolerated and celebrated in books, movies, music.
If I'm trying to make a business out of child porn, sure try to prosecute me. I believe selling other peoples' pictures without consent should be illegal in any case, specially if in demeaning circumstances. If I'm just sharing it, though disgusting it may be, the law should not stick it's nose in it. Just like it's legal to share books on how to make bombs and poison people.