They’re a space agency. They employ astronauts. The whole reason for them to exist is to put people into space and space science and exploration. A NASA without a manned launch vehicle is like a cab company with cars, like an airline without planes.
OK. That’s a valid argument. A counter-argument is that hiring a contractor to do routine travel is less expensive. NASA hasn’t actually OWNED a routine launch vehicle of any kind for many years. Ownership Delta and Atlas, for example, was spun off to ULA years ago.
Does NASA own the SLS/Artemis hardware?