if it's a crime to view abuse of children, why is it not a crime to view abuse of adults? You can watch TV programmes every week where CCTV has captured people being kicked, punched and abused. What's the difference between that and it happening to children? Surely, it should be stopped?
People who seek out footage of children being abused do so for sexual gratification.
I have seen on Crimewatch reconstructions of children being physically abused in a public place - the purpose of showing that is hopefully to catch the perpetrators.
With the exception of acts of terrorism, knowledge of any other criminal act is not a crime in itself. Therefore viewing something would not be a crime. Child pornography is a specific criminal act so is different.
This is however more of a moral issue than a legal issue.