Why shouldn't the government collect biometric data unless absolutely necessary? Things like this can happen to it:
The stolen database contained the name, date of birth, national identification number, and family members of 9 million Israelis, living and dead. More alarmingly, the database contained information on the birth parents of hundreds of thousands of adopted Israelis---including children---and detailed health information on individual citizens.
It's a good, short write-up from Fast Company. Read the whole thing and pass it along.