They're one of those elements that would've had a bit more meaning in the multiplayer side of the game. (There was also a cool cut feature where the Shrike escape pod could fly around on its own with a single laser cannon!)
Please take what I say with a grain of salt, but in terms of the WC games, I think you have useable tractor beams in 2, Academy, 4, Privateer, and Privateer 2: The Darkening, I have only played Armada once, so I can't say for certain.
Tbat's a pretty good list! There's also a tractor beam in Wing Commander Arena, which makes for a pretty solid tactic where you can tractor in an enemy ship and shoot at it in the process (or run it into a torpedo!).