I find that surprising, even in 2010 it was difficult to find illegal content on Freenet unless you were looking for it - and certainly in recent years it's virtually impossible, the default indexes are carefully vetted.

In any case, the original Freenet was never going to be a general-purpose replacement for today's centralized services as it can only handle static content. For the past few years we've been working on a sequel to Freenet that is much more general-purpose, you can learn about it at https://freenet.org/. While the original Freenet was analagous to a decentralized hard drive, the new Freenet is like a decentralized computer.

As part of it we're building a decentralized reputation system (based on a "web of trust") to address illegal/offensive/objectionable content.