The hammer analogy has its limitations here. When the task is simple (hitting a nail), a simple and good design lasts. When the task(s) is/are complicated, depend on context, are tied to human understanding, knowledge or training in using machines, then design could benefit from both refinements as well as radical and creative thinking. I also don’t think that just because we have a good design, even for a hammer, we should stop people from challenging norms and thinking in bold ways. Here’s a contrasting example to hammers - chairs. The objective is simple, to sit on it. The design innovations still continue to this day, on how a chair can be structured. There have been interpretations of chairs that challenge the very notion that chairs need legs.