Re: Crew members and their roles
As Janeway had a science background, maybe the producers figured she would assume the role of science officer when needed. She frequently took an active part in scientific investigations. It might account for Genevieve Bujold's insisting she wanted to play a scientist rather than a commander, based on what she'd been told about the character.
Dr. Howard, Dr. Fine, Dr. Howard: For duty and humanity! --Men in Black (1934)