Possibly even more important than knowing where to hit it (what to code), is knowing where not to hit it (what not to code). Hitting the thing in the wrong place can lead to catastrophe. Making a code change you don't need can blow up production or paint your architecture into a corner.

AIs so far seem to prefer addition by addition, not addition by subtraction or addition by saying "are you sure?".

This doesn't mean that "code is cheap" is bad. Rather, it means that soon our primary role will be to guide AIs to produce a high proportion of "code that was cheap", while being able to quickly distinguish, prevent, and reject "cheap code".