I don’t think there is much use for Application roles except for client server applications.

Most of our applications are web based and end-users do not have logins in the database. Access to the database is only given to the service account that the web site is running under, and this account does not have any elevated privileges. Security is handled by limiting access to the web app to specific Windows groups. Finer grained security is handled within the application by letting an application administrator grant or revoke access to specific application functions.