It could have practical application when any of those constraints are violated: - Most crypto schemes haven't been proven secure in any absolute sense, only re

It could have practical application when any of those constraints are violated: - Most crypto schemes haven't been proven secure in any absolute sense, only relative to other problems we think are hard. - Protecting that entropy can be hard. - Crypto is expensive. If you need a high bit-rate (another comment mentioned GPU Monte Carlo) then integrating these on-chip could be cheaper than mangling the same entropy source over and over. - Adding to the above, using the same entropy source in multiple places can be prone to non-obvious bugs and race conditions where you use identical or correlated random bits. Also, less secure applications often cannot get by with dropping the cryptographic constraint, and it might not be obvious when it can be safely dropped (even ignoring the arguments that usually crop up in these kinds of discussions like how for an online poker match you probably do need secure RNG) -- e.g., non-crypto RNG is prone to linear dependences and other problems which can significantly and qualitatively change the nature of all but the most trivial simulations.