I do hope you are not inferring that those of us who have purchased object desktop in it's entirety, as well as some of the exclusive skin suites or icon suites etc, are not "a little invested in the place", GM !! Because by only allowing people at apprentice level or better direct access to the email addy's of skinners etc, you are directly dis-enfranchising those of us who most need the direct assistance of the skinners when we encounter problems.
As an example, Jebland made a wonderful Object Bar to go with Treetog's excellent Copper Deck II Window Blind. I experienced some small problems with it that I would have had no idea about fixing, but as I had access to Jebland's email address, I was able to send her a screenshot of the problem, which she then worked on, fixed, & sent the amended file back to me, all within a day or so. Without direct access to her email address, I wonder how long this process might have taken? As things stand, I am still using her Object Bar, but I doubt that would have been the case if I would've had to wait for a longer period of time before the fix was made available.
Therefore I would urge you to look look very carefully at ALL the ramifications of limiting email addy access to "The Chosen Few"

before instituting such measures, as some could interpret such actions as smacking of elitism. However, if a member declines to show their email addy in their user profile, then that is their choice, and they have every right in the world to make it.