The GDPR simply requires to store sensitive data (like names and email addresses) in a safe manner. This is a requirement, not a recommendation. If your WP site is ever hacked (which is not unlikely for WP) and you didn’t encrypt your data as a security measure, you may have a really big problem. Names, email addresses, gender, etc, should ALWAYS be encrypted. It is very easy to implement, the tools are just there. Just do it!