Data was the Operations Officer on the Enterprise, and he was a Lt. Commander. I don't think a higher rank for that position is a waste of time, despite Voyager being a much smaller ship. Ops is still Ops, no matter the size of the ship.
Operations is a department.
It's more about HR than scanning for lifeforms.
Kim has to organize for some one to always be sitting in that seat, 24/7, and then write reports on how well they are doing their job, and what actually happened in each shift, which he has to send to Chakotay, and cc to Tuvok, every damn day.
Kim is in charge of Ten enlisted crewmen at any one time, and becuase he can't give orders to any one of the same rank or a higher rank, his staff can't be Officers.
Data on the other hand is in charge of probably more than ten Lieutenants at any one time, and has to be a lieutenant commander to give orders to lieutenants.
It's also about the missions that the ship is supposed to go on. Picard wants experienced people that can handle anything, because he is sent into the shit, or he waits on the edge of Federation Space for the shit to come to him.
Janeway is a murderer.
She picked a disposable crew that didn't mind going into the badlands and dropping two tricolbolt devices on a commune of hippies, who would not need a thousand hours of therapy to cope with all the blood on their hands. Actually if Kim was the Editor of the Academy paper, and he covered the rise of the Maquis, which he was and did... Was his coverage more like Inforwars than CNN, because Janeway picked him out of the fresh crop to murder a few thousand Maquis without a single blemish of regret.
Operations fire the weapons, right?