Shon,
Your assumption that there is 'too much potential' for abuse is ridiculous. Of course, as with ANY work practice in ANY workforce/industry, systems can be abused; but not to have a system that can SAVE LIVES because it MIGHT be abused, is simply fallacious.
Generally, pilots are a highly professional and conscientious group of people. As a group we have been selected EXACTLY because we are similar - we have been through batteries of tests that confirm our personality types (search 'pilot personality traits'). There are always a 'few' who will abuse the system, but the majority will use it wisely.
Fatigue management is a vital component of aviation safety, and anyone who doubts it's necessity is simply un-educated in the field.
Simply because you can't always 'see' fatigue, does not mean it isn't there.