You can ask for better work without making someone regret showing you their first attempt.

The first version is the most fragile thing a person hands over, because it is the moment they find out whether showing you was safe. Feedback that treats it as a finished product rather than a beginning teaches them to bring you things later, more polished and less honest.

Start by saying what the draft already does, specifically enough that it is clearly not a formality. Then name one or two changes and be plain about them, because vagueness is its own unkindness. End by asking to see the next version. Wanting more from someone and being glad they showed you are not in conflict.