First, sampling atmospheric noise is not good general entropy source, because it needs careful setup to ensure that what you are sampling actually is atmospheri

First, sampling atmospheric noise is not good general entropy source, because it needs careful setup to ensure that what you are sampling actually is atmospheric noise and not some signal, also such noise might well be unpredictable, but certainly is not secret (ie. not readily usable for cryptographical purposes). Second, there are significantly cheaper ways to get quality entropy in modern digital system. Relative timing of various internal events in system with multiple clock sources is one of the meaningful sources. Also, purpose built hardware RNG integrated into some silicon is essentially free (and mostly cheaper than it's interface circuitry). The problem is not that system does not have usable entropy, but that application tend to not use the good sources that are already there (ie. /dev/urandom, CryptGenRandom/rand_s and such)