tl;dr: propositions in bold italics
On the one hand, quality control is paramount for SE success, so posting guidelines need to be adhered to. New users are often unfamiliar with SE rules. This can sometimes result in a somewhat blunt response to homework questions, for example. Although this often happens in complete agreement with SE guidelines, this nevertheless has already been highlighted as an issue. Similar discussion about homework questions.
Taking this a bit further, I speculate that this may lead to a significant number of younger users who are alienated by this "harsh" response, especially children who have decided to join the community and made a first clumsy post. Personally, I have the impression that the average age of users posting their first question is dropping, especially on certain forums (I'm thinking of Chemistry, but that may be just a feeling, I have no data to back that up).
I feel that SE should be as inclusive as possible in regards to potential young members, and that it would be a significant loss to the community if their interest is bashed away by an indiscriminate policy (for me, this is especially objectionable in SE's scientific branches). I realize that SE's core idea of up/downvoting posts does not bear an offensive quality, but that's an adult concept. SE has grown far past its bare core and now faces the delightful perspective of answering kids' questions. Something to be cherished, I'd say.
User anonymity makes an age-based response impossible. Therefore, I'd argue for a set of "canned answers" for the most obvious breaches of SE rules (most notably, homework questions that don't show effort) that are formulated in a friendly manner and invite further participation. Maybe they can contain fields that need to be filled in, like links to existing answers.
Alternatively, maybe it would make sense to create a rule that requires some basic form of friendliness in all answers, especially those mark the question as inappropriate? This seems harder, because friendliness is a subjective quality.