However, _that_ website is not served over HTTPS, which would seem to make it a prime target of MITM. Do you happen to have an HTTPS link to obtain these certs?
Alternatively, the DoD certs served up securely by Symantec: https://knowledge.symantec.com/support/eca-support/index?pag...
Well, also because an HTTPS page would create a chicken-and-egg situation. How do you download the root certs if you can't see the page because you don't have the root certs? etc
So, programs are downloading certs automatically, where they would be even less likely to properly check checksums against a secure site. And create a additional small attack vector.