It's about as useful as the current TV rating labels, that is to say, NOT effective at all. You're right. Filters do a much more effective job.
As for Government regulation, forunately, Justice Kennedy seems to agree that filters are more effective, and less intrusive, than the Legislation passed by Congress, and said as much in remanding Ashcroft v. ACLU back to the District court for trial. So that's a plus.
But it doesn't help Jeff, Max and the others who are facing prosecution. Those cases are going to be decided based on the Miller test, and only the Supreme Court can decide if more recent decisions (like Lawrence v. Texas) render the Miller test obsolete. Check out Rob Black's case for more on that. (U.S. v. Extreme Associates)