This neocon fantasy that the best way to be secure is to exercise facism-level military dominance over the galaxy is self serving nonsense that does more harm than good in the long term.
I think you could argue that the Federation not using all means at its disposal would be a disservice to its citizens. Commodore Decker says in "The Doomsday Machine" that the primary duty of a Starfleet officer is to protect Federation lives and citizens.
Commodore Decker wrote:
Our primary duty is to maintain life and safety of Federation planets. Do you deny that?
In a universe where there are civilizations that make Starfleet look like they're still using sticks and stones, it would be silly not to study and use materials that can put them on more level footing with those civilizations. Certainly there are ethical considerations, but you can't allow those considerations to stand in the way of protecting your citizens.