That assumes the situation where the password hashes are stored in a way that is less secure than the actual data that the attacker ultimately wants access to. That must not be a very common situation.
The passwords will not be of any use on any other system. This would eliminate password reuse.
Accessing a users data is not the only reason for hacking their account. Performing actions on behalf of a user is just as much of a threat.
Edit: also, if an attacker dumps all the data today then loses access to the data tomorrow, having access to my password hashes means they can access my account and data later.
The passwords will not be of any use on any other system. This would eliminate password reuse.