I can think of a few possible reasons:Simon_Jester wrote:Plus, quite frankly I can't understand why anyone in Star Trek who hasn't explicitly promised not to would ever NOT use cloaking devices on ships that could conceivably need to sneak up on someone. It's just a good idea all around for military purposes, and for that matter for peaceful purposes if you're trying to avoid conflict either through deterrence or through denying potential aggressors any easy targets.
So for me, the question isn't "why do Klingons use cloaking devices," it's "how come the Cardassians, the Borg, pretty much the entire Delta Quadrant, the Dominion, and so on don't?"
- To keep cloaking devices able to defeat advancing sensor systems requires constant, expensive, R&D. Too expensive for many smaller civilisations to afford.
- Using cloaks causes diplomatic issues because they make it much harder for other civilisations to trust your civilisation because they know you are up to something that they can't see. Especially when an explorer accidentally crosses a border they didn't know about.
- The governments of the various civilisations don't trust their captains with cloaking devices.
- SFDebris once commented that the standard Borg greeting was one that conveyed a message of inevitability. Approaching under cloak would run counter to that message. Or Cubes might be too big to cloak easily.
- Coordination issues. For civilisations that fight using fleets, they have to know where the other fleet members are to prevent crashing into each other. But that means communication signals which could be picked up by whoever you are trying to hide from.
- A civilisation believes that their tech is so superior to that of everyone else (that they know of) that cloaking is unnecessary. Why sneak up on someone when you know that there is nothing they can do to stop you if you do decide to attack them, even when they see you coming ?