That's especially true if the individual is traveling. Or, try the political process. Bar the use of such information and you achieve two undesirable things. First, you may end up with lots of people who ARE NOT interested at all in being solicited. Second, you may forestall fundraising by those espousing minority views.
Privacy is a legitimate public policy concern.
Kenneth Robinson is a Washington communications attorney who was senior legal adviser to Federal Communications Commission Chairman Alfred C. Sikes during the Bush Administration.