Gun control debate aside, why is anyone ever surprised that a special interest group like the NRA would act in anything other than a self-serving manner concerning its own interests? To expect the NRA to condemn gun ownership, lament the availability of all types of guns, or call for stricter gun control is sort of like expecting the ESA 5to come out and say "Yeah, games are too violent and cause mass shootings so we think that the government should pass laws limiting what content developers can put in their games". The idea is crazy - why would any special interest act contrary to the very interest it was established to protect?
That said, the NRA is a failure because it caters to the most fanatical of gun owners and gun rights advocates and does next to nothing to promote responsible gun ownership from what I've seen. It deflects and sidesteps instead of helping formulate practical solutions to the problem of mass shootings.
“The greatness of a nation and its moral progress can be judged by the way its animals are treated.”
- Mahatma Gandhi