Tactical Team (also sometimes referred to in-game as Security Team) is a very good ability to restore lost crew to increase hull regeneration and remove Tactical debuffs. It also serves a purpose as providing the player with a reasonable boost to projectile weapons and energy weapons. Finally, it will also help counter the Boarding Party ability.
So by not using them you're missing out on:
- crew regen
- hull regen
- debuff removals (and boarding party)
- dps increase to torps & beams