One reason to care about this is that random number generators are a very lucrative target to attack for security services. See for example ECDual https://eprin

One reason to care about this is that random number generators are a very lucrative target to attack for security services. See for example ECDual https://eprint.iacr.org/2015/767.pdf https://eprint.iacr.org/2015/767.pdf or Linus Torvalds' answer about NSA approaching him about a backdoor: https://www.youtube.com/watch?v=wwRYyWn7BEo https://www.youtube.com/watch?v=wwRYyWn7BEo