A what if scenario would be a great addition. For example, if the course has Assignments, Discussions, Quizzes, etc. the ability to choose a "don't include in Total" would be a quick, easy way for Teachers to see how their students would have done had Discussions not been included in the Total score. Students scores wouldn't actually be affected, just a way to give instructors a quick way to see what grades could have been if set up a different way.
This suggestion is not part of the current scope of the New Gradebook, but there is an existing feature idea that you can add your vote and use case to. https://community.canvaslms.com/ideas/5185-what-if-grading-for-instructors