My preference is that it is retained due to its ability to provide a contact point for members or visitors who do not regularly visit the site. Specifically, I have a forum that attempts to put long-lost-friends in contact with each other, but it doesn't necessarily mean they are registered members, nor that they understand or will use a PT.

People like that it is more private, i.e. does not store data on the site.

So it can stay.

Also as Fletch says, Guests can use contact-member but not PTs.

Moved contactmember to a separate addon so site's can remove it if they choose to.