That's not a fair comparison. If you looked at one of the early slides in the presentation that the slide in question came from, you can see that NASA decision makers are trying to balance three conflicting objectives: 1) Budget realities, 2) risks, and 3) benefit to stakeholders. This is no different than any corporate board. The stakeholders of NASA are the American people. As such, NASA has a duty (implicit or otherwise) to bring as much benefit to the American people as possible. It does this through several avenues. One of the biggest, and one that is often overlooked is the amount of knowledge that NASA has generated. You show me one for-profit company that has been as open as NASA at making all of their information public and available. [1] Secondly, it would be naive to think that NASA does not have an obligation to provide benefit to their stakeholders by providing jobs.
With this framework in mind, what objective is the car designer trying to balance when deciding to use more steel? If the writer decides to use more words, what objective are the trying to meet? The first case you bring up is ridiculous and I'm not going to address any further. The second case is more fair. The novel writer does have to balance clarity of writing and the amount of pleasure they bring to the reader. Someone buying a 50 page book is going to feel pretty ripped off if they read it in 30 minutes. Why are the Harry Potter books so damn long? Because people love to read them. She could have just as easily written the same story in a lot shorter format if she had so decided.