Because it takes non-zero work, and doesn't add much value on top of SSL/TLS, which got wide deployment first. As far as I understand, IPSec + DNSSEC gets simi

Because it takes non-zero work, and doesn't add much value on top of SSL/TLS, which got wide deployment first. As far as I understand, IPSec + DNSSEC gets similar security guarantees to SSL/TLS without identity certification, so once you have one there isn't any real economic incentive to put massive effort into developing the other.