Flatbusher, there was no such thing as Mr. or Mrs. at one time, and people referred to each other by their names. Are you suggesting they were committing an immodest or disrespectful act?
Anyone who wants to be called Mr. Mrs. Dr. Professor, Rabbi,or whatever their title may be, should be. But some people really have no such desire, and THEIR wishes should be respected, as well. My Rebbetzin does not even want to be called Rebbetzin. She asked to be called by her first name, and if someone says Rebbetzin or even Mrs. ________,she gently says her first name to them.