There definitely are legit use cases for it and in an ideal world, I think all traffic should go over onion routing by default to protect them.
But in reality today besides a handful of idealists (like me some years ago), and legitimate users, like protestors under oppressive regimes - I would assume the biggest group with a concrete interest to hide would be indeed pedophiles and other dark net members and therefore use it.
I'm pretty sure many people use Tor for other things than journalism and CP.
Tor is a privacy tool. Much of what we do in our lives is on the internet, and privacy is important. Tor helps people enjoy privacy in a medium that they are increasingly dependant on.
Tor also helps you to increase your average loading time of a webpage to 10x. That's a very good deterrent against using it if you don't need it for some reason
are you implying that Tor is not used for illegal or immoral purposes? (I took out the primarily that you threw in to make your argument stronger because that made my argument stronger, and I took out your scare quotes because morality doesn't scare me)
I have no idea who is using Tor other than that I heard it can be used by people requiring privacy from governments, e.g. whistleblowers. It also seems to have broad support from the tech industry so I'd be surprised if it was in fact primarily used for illegal or "immoral" purposes. That's why I'm asking.