I occasionally leave a message for someone but I don't really see the value of having it publicly viewable.
It is also not possible to have an exchange - when I get a message on mine is it best to answer it there? or go to the other profile? This is always confusing - and when I feel confused I sense an opening for alternative design.
I am pondering a Gossip Forum? (working name only)
Possibly a Friends Forum? Neighbours Forum?
This would be forum where each user can have a (potential) personal thread
though it would need activation by its user posting a welcome message
OR by someone else posting a message for that user.
On the Profile page we see the thread as a normal thread which we can click to view or add a message for the user. The user receives notification and Alert on it.
If the user has not activated their potential thread the location on the profile page shows
"Would you like to leave a message for username?"
The user sees
"Click here to post a welcome or starter message for your visitors."
The user can opt to block having a Gossip thread.
They can also blacklist selected users from accessing, or posting on it.
They can whitelist selected users so that others cannot access or view it.
Users cannot open a topic thread in this forum.
Messages act like normal posts and appear in What's New unless
the user has opted for a private (whitelisted) thread, or has blocked having one.
At the top of the whole forum page a message reads
"All members can have a personal thread in this forum.
If you have not opened yours click HERE.
If you want to find a particular member thread use the THREAD SEARCH on their name.
CAPITALS = links
If the member has blocked having a thread, or opted for privacy whitelist
"This member has opted not to run a Gossip thread."
"This member has set their Gossip thread to invitation only.
You can ask username for an invitation via a CONVERSATION with them."
If no messages have been posted on that thread yet
"Would you like to leave a message for username on their thread?"
This would have the advantage of holding user focus on the forum system.
To me this is very important not to use other facilities where the rich and varied services of a forum can do the job. I see diluting forums as undesirable.
It is a consideration that newer users do not much enjoy the learning curve on different methods of communication. The more they can stick with the forum/ thread style the better - they will learn it in depth, and make better use of it.
This whole suggestion would have the added advantage of freeing the space on the profile page for information about the user which is currently hidden under tabs - info like location, homepage/s, occupation, birthday, join date and custom info.
User's could also upload a picture or two or three which could also automatically appear at the top of their thread!