Is there a reason Spock, Scotty, Sulu and Chekov are referred to as "Mister" as opposed to their rank? We have ranked officers like "Captain" Kirk and Lieutenant Uhura, as well as descriptive names like Doctor McCoy and Nurse Chapel. Was this Roddenberry's attempt to demilitarize Starfleet bt emphasizing "Mister" over ranks like Lieutanant Commander or Ensign?