Good point. Now that we are getting rid of some of the other options, we don't need to worry about consistency with them, and I think we should just use "--statistics".
The point of the --with flags was to future proof commands to preserve behavior in case the defaults ever changed.
This would all be a lot simpler, and the --with switches would all be unnecessary, if we didn't decide to make exactly one type of dumpable object (statistics) off by default but only in one of the three commands (pg_dump).
I think we're creating lasting confusion for the sake of short-term convenience.