When donor enters billing address w/cc, billing address becomes primary

When a donor enters a donation via contribution page and has to fill in a billing address, this address gets put in to CiviCRM and made primary.

This is problematic – some users have very good data that they want to use for doorknocking and direct mailing that is marked as primary but gets supplanted when a credit card donor gives a contribution.

Billing addresses often don't correspond with the mailing address where people want to receive mail. Some of our clients are also using counties, which the billing address doesn't collect. By becoming primary, it weakens the address data that they have in the primary address fields.

This shouldn't happen by default. It should at least be an option (make credit card billing address primary?) Can we make it optional to make the billing address primary?