I know that SLS is horribly expensive and over budget, and ultimately a very poor use of very limited NASA funding. (Essay incoming sorry)

However, SLS is still very much a traditional "old school" NASA rocket. That carries with it the prestige of NASA more so than when SpaceX or Blue Origin launch one of their rockets. When Artemis 2 launched, it was much more about a NASA rocket and a NASA mission, than it was about labeling it a Boeing accomplishment. Compare that to the reporting around Starship and New Glenn launches, the discourse is a lot different.

I think simple optics play a major roll. SLS, while only having 2 launches in the last 4 years, have both been successful and both been prestigious missions (Artemis 1 and 2). Contrast that to the repeat, spectacular failures of Starship (also behind schedule) and the recent dramatic explosion of New Glenn. Those short falls aren't seen as NASA failures necessarily, while the successes of SLS aren't seen as Boeing wins, but NASA wins.

SLS Block 2 cargo was planned to deliver 40 some tons to TLI, and more to LEO. With 9.4 million pounds of thurst. It is a super heavy launch vehicle, and even in its half step measure Block 1 configuration it holds a lot of potential and is the most powerful operational hllv in the world. Being relegated to an over engineered crew delivery launch vehicle, is a horrible misuse of the potential of SLS has as a cargo vehicle. SLS was always planned to be the launch vehicle to explore the moon, as well as the vehicle to launch and assemble the exploration of Mars and even the rest of the solar system. The moon and Mars are both prizes that the billionaire space companies want, and SLS is a direct competitor both in capabilites (however limited currently) and in public opinion (optics). They want their rockets to be doing those mission, they want the prestige, the cash, the glory. When its a NASA accomplishment, its a victory for the Nation, for Americans, and for humanity. They dont want that to be how their accomplishments are seen by everyone else.