The current settings in 'Configure Portals' reads ‘allow portal users to be anonymous’ however I’ve since confirmed that there isn’t an option to allow customer's to select this option if preferred. The selection of this box in the configuration means that all users will be anonymous. Without ticking this box, user names are visible. It would be good if there was an option on the idea submission page for the user to choose whether they wish to remain anonymous. Due to Data Privacy, the default option to hide portal user names is safest which is expected to reduce the use of the ideas portal.
Thank you for your idea. First and last name are actually optional fields for portal users creating their account. If they choose to leave these empty, their name will show on ideas and comments in the portal as "Guest."