The problem with optimizing for less lines of code is the same as optimizing for unit tests: the less robust your code is, the better off you are.

Meaning, it's trivial to write unit tests when your code is stupid and only does happy path stuff and blows up on anything else. So we say "you need 90% coverage" or whatever, people will write stupid frail code that barely works in practice, but that is easy to unit test.

Similarly, if we say "do it with the least amount of code", we will also throw any hopes of robustness out the window, and only write stupid happy path code.