It is intentional. The archetype should set its own value for all fields. Only exceptions are date which is set by now always and title which is provided by the user through the file name.
Note: hugo new does not automatically add draft = true when the user provides an archetype. This is by design, rationale being that the archetype should set its own value for all fields. title and date, which are dynamic and unique for each piece of content, are the sole exceptions.