I think this is a great way for organizations to protect sensitive information from being accidentally shared. The ability to customize the experience via GPO settings gives administrators a lot of flexibility in how the pop-up is displayed and what information is included. For example, administrators can choose to show the pop-up only for certain types of sensitive information, or they can require users to provide justification before sending an email that contains sensitive information.
I think this feature is especially important for organizations that deal with a lot of sensitive data, such as financial institutions or healthcare organizations. By using the oversharing pop-up, these organizations can help to prevent employees from accidentally sharing sensitive information with unauthorized individuals.