The reports still need to be made so the FTC,FCC and other agency's have the info and can see whats going on and also have this information available to try and track them down and get patterns etc. Not exactly useless as you seem to think!
Did you expect things to happen in a hour like on CSI? Real life doesn't work that way I'm afraid.. Some of the scammers are in foreign country's and it takes two to co-operate and make the catch and shut down. Then take the fact that the some agency's have far less folks working.. 30 agents to cover the whole US isn't a whole lot now is it?
It does happen, just doesn't happen as all of us would like it to! You may not hear or read of everything either.. Unless you actually spend some time over on the FTC & FCC websites. But here's a few of whats happened lately.