Currently, users are not able to delete the original creator of the flow. Which can be an issue when they leave the company or are no longer working on it. The trash can next to their name is grayed out.
Yes, this would be useful if the creator of the flow no longer should have access (for example, there is sensitive data visible in outputs of the flow runs). As I understand, if the owner is removed from AD because they've left the organization, then they'll automatically be removed. But sometimes the person just leaves the project or office.
Yes this is necessary. Our programmer has passed away and it is disconcerting to staff to see emails/tasks still coming from him due to the flow he created.