I am simply stating the obvious, that NX is not a panacea for security
I think we all agree with that. No one system or technique is a panacea for security. All NX does is block a very important security weakness that has been used to create a lot of damage very quickly. It shores up one of the weakest points in the security of many servers. But it isn't, couldn't be, and was never meant to be a panacea for security.