If people in government weren't so concerned about controlling people, it might be useful. Medical matching for organs and catching crooks are two great reasons for DNA. The problem, as with everything man tries, is that we have limits of wisdom as far as who is given this power. Take the present administration in the U.S. There are even concerns among some that President Bush might try to prevent the next election. That's how far from the so-called freedom he preaches we've gone. Media might as well just admit they're government controlled and the wealthy might as well quit pretending everyone thinks they're nice.
The "free" world is not so free, which is the ultimate result of lack of real wisdom in leaders across the world. Most leaders, if not all, are more concerned about getting their wealth than taking care of the people in their "care". For these reasons, DNA libraries of every citizen are nothing more than an attempt to treat us like cattle.