Ethics professor scandals in particular are a case which highlights the problem. While there may be sincere examples the scandal ridden ones are like cynical constitutional law professors: they clearly studied it to try to find loopholes around it instead of to uphold it.
Despite that the field of Ethics has vast theoretical potential in one subarea: understanding of incentives, including perverse ones and how to properly craft systems of them. "Alignment" is the buzzword for the latest moral panic about AI. One of the many problems with it aside is that humans sure as hell aren't aligned. See corruption for an example of what bad systems get you.
That's not a great track record.
https://www.newyorker.com/news/annals-of-inquiry/sam-bankman...
Unironically privileged Westerners could be doing considerably more good in the world by protecting their freedoms in their own lives, egoism would be much more effective there.
Metaphysics is useless similar to any foundational research. Theoretical (as opposed to applied) mathematics is also largely useless. Nobody expects to use transfinite set theory in practice. Or the cosmology of the early universe, for that matter. Or an interpretation of quantum mechanics. A lot of non-foundational research is also useless. Research on the evolutionary origins of the ichthyosaurs. Or the surface properties of Pluto.