For example, if Freenet were to reach scale, it could eventually need some kind of economic primitive around it. Something similar to how Filecoin handles decentralized storage, but for app state. One way to do this could be paying peers to keep app state available, serve it reliably, etc. and prove they are doing so.
So there are a lot of possibilities but for now users are motivated by a desire to see the network succeed, and that seems to be a sufficient motivator at our current scale.
- You participate in a secret cabal, and don't want participants' identities be visible to each other.
- You're a journalist, and want to give your informants in sensitive matters, or from oppressed countries, a way to securely interact with you, so that you won't be technically capable of reporting their identities.
- You're selling illegal goods or services.
I'd say that in the first two cases I would consider running a separate copy of the network, because it apparently involves one supernode, and I might want to control the supernode (or maybe not).