However, we have to try to come up with some. The idea that if you simply take away the metrics we will automatically improve the product is flawed.
Consider rewrites that burn a year of time for dubious value. Or fancy "refactors" that are really big heavy redesigns that lock you into abstractions that don't make sense in six months. Or devs that open 2000-line after 2000-line pull request...
At that point, code metrics aren't just about performance management, it's about me wanting to make sure I'm actually moving the code in the right direction.
Something I'm very interested in is if dev commit patterns line up with different types of work, and if some of those are "behavior smells" - e.g., not refactoring things one at a time, and getting your tests happy in between each move.