Current problem
Sometimes you want people to DM you without changing your DM settings or add them as a friend.
Proposed change
An option in the context menu of other user's profiles, something like, "Allow DM", with an option to specify a duration (or indefinitely) that the access will last. Beyond the specified duration, the DM access will be default.
Additional information
This can be applied to other privacy permissions like View Bio, Allow Call, or Add to Group too.