I love that in new quizzes I can make a comment on an individual question, but I would love if students could then reply to those comments and then resubmit the quiz (so that teachers are notified that they need to re-grade the assessment).
We have a system where students can get points (or half points) back if they correct an incorrect answer on a quiz. It's really about using assessment to support the learning process. Instead of just telling them that it's wrong and they then never really learn what is correct, it's empowering them to find the correct answer with maybe a bit more guidance from the teacher's comment.
Our institution is an Australian Vocational school, which means it is competency based and therefore this process of correcting wrong answers is actually legally required (and very difficult to do on Canvas quizzes), but I could see that it would be beneficial for other teachers who hold a similar pedagogy.