I would say the use case is to not become a Snowden. "The public" doesn't really mean anything (reference some of Ayn Rand's work) because it abstracts away the individual. Individuals other than Snowden have just as much reason to use Tor as Snowden by virtue of the fact that Snowden has to. That's the whole point. If we had nothing to fear then sure, no one would need to. Snowden proved that everyone has something to fear. Hence Tor.
I am a regular guy who runs a Bitcoin node. Why should I use TOR? The use case for nostr:npub1sn0wdenkukak0d9dfczzeacvhkrgz92ak56egt7vdgzn8pv2wfqqhrjdv9 is clear, but what about the public? Again, no irony.
Discussion
That said, the individual must decide which tradeoffs to accept and when. For example, sometimes I just use Mullvad because it's faster and I'm okay with the tradeoff.