Actually, simulating explosion sound in space makes a lot of sense. What's a better way to signal there's an explosion than "boom" sound? Afterall, the source might not be easy to identify (as it just exploded) and all the information you can have is the magnitude of the explosion and it's distance, both quite easy to intuitively handle by a simulated sound cue. Verbal cues are good for more complex messages, but they carry the risk of a "helmet fire" (pilot overload). Sound cues are very important when whatever they indicate needs to be handled when, say, having your eyes fixed on a bandit. They're usually in form of various beeps and tones in modern fighters, but in space, you have to compensate for a large amount of verbal cues lost when you exit the atmosphere. So, it's not a stupid cop-out but a reasonable explanation.
I'm looking at some of these sample verbal warnings on wikipedia. I almost wonder, if they've got these down, with the computer identifying such threats, maybe by the time we've got ships capable of space combat and all the tech that goes with it, maybe pilots will be obsolete and computers will be flying the ships and people of that era will be scoffing at old sci-fi flicks and games at the notion that a person would be piloting the vessels.
I don't think it will happen by the time we've got space combat capable ships (which will hopefully never happen and won't be needed, there are treaties prohibiting this). This will happen earlier. Make fun of UAVs and their operators all you want, but they're the future (and before that future happens: How many UAV operators are needed to change a lightbulb?
).
If you think about it, space combat would likely resemble naval combat with infinite sensor range than air combat. "Space fighters" are likely to be spaceplanes good for planetary defense, capable of rapidly responding to a threat in orbit. They'd have their niche, but won't be nearly as important as airplanes in naval battles.
