I don't want "Guests" to be able to suggest an idea :)
Thank you for the request. Currently, when users sign up to create an account, we do ask for the First and last name.
However, if a user creates an idea before they have created an account, we only require the email address. We do this to offer a path with least resistance (to encourage Ideas to be added). A user does have the option to then Edit their profile to add name details.
At this time, we do not have plans for updates in this area based on current priorities and the above logic. However, you could consider leveraging the email templates to remind users to add their name via the Edit profile link.