> blocks if you don't have enough entropy

Which, in most cases I can think of is a rather undesirable behavior.

I would really be interested to understand which use cases justify using an actual blocking call to retrieve random bits.

I've always been under the impression that the only valid use case for raw entropy bits is regularly seeding crypto-hard RNGs that can generate an endless stream of random bits (à la /dev/urandom).

Looking forward to being educated on the topic.