I didn't notice where you posted your question, but I agree with Deano on one of his points. The developers forum is basically there so that people who find bugs can let Deano know.
Suggestions is a place where you can suggest that something be added or removed from the script, but please keep in mind that the Primary focus on Cheetah at the moment is to remove unnecessary code (Flash etc) and fix known bugs in the Dolphin script.
Personally, I'd like to see the kind of questions you're asking placed in the "Answers" Module because they'll eventually get lost in the forum and future users may have problems finding them.
Not so with Answers. Another nice feature with Answers is that the person asking the question can vote on the best answer.
Maybe we can kick Answers off if you ask your question about Social network Links again and I'll respond. That way others can see how Answers actually works.
Now my ten cents worth about your question here.
I would not remove that link. In my opinion it's one of the best things about Cheetah's mail form. I use the link every time I send a message because the member also receives an email as well. Some members only visit a site once a week, or only when they're jolted into doing so. On one of my sites, some members have dozens of unanswered messages either because they rarely visit the site, or they don't see the Red Blob next to their Mail Icon.
Members who send messages that are unanswered become frustrated. They can easily develop a bad feeling about the site and eventually stop using it.
By allowing members to send a message to the person's email as well, there's a reasonable chance they'll go to the site and respond to the message.
The person sending the message never sees any email addresses and I ask my members not to publish their emails publicly.
The message system does have a timer of one or two minutes to stop people flooding the mail box. You may wish to increase the time. Deano would need to help you on this one I think.
It seems that members can currently post a maximum of 10 messages every 24 hours. You can experiment with this.
admin/settings/membeship levels/System Levels/Standard/Actions/Send Messages (Double Click the link)
On my sites I've left it at 10 and nobody has abused it.