Choose your random number generator carefully

Bruce Schneier has just released his overview of the recently released US Government's official standard for random number generator.

His disclosure of a trap door found in the Dual_EC_DRBG is something of a worry:

This is scary stuff indeed.

Even if no one knows the secret numbers, the fact that the backdoor is present makes Dual_EC_DRBG very fragile. If someone were to solve just one instance of the algorithm's elliptic-curve problem, he would effectively have the keys to the kingdom.

And his recommendation to selecting a random number generator:

My recommendation, if you're in need of a random-number generator, is not to use Dual_EC_DRBG under any circumstances. If you have to use something in SP 800-90, use CTR_DRBG or Hash_DRBG.

I wonder what is the purpose behind all these.