reality? When the ships are using a hyperspace drive bubble to move at nigh-FTL speeds even before hyperspace itself?
In addition, while not being a star trek fan enough to instantly know the reference, there are several episodes with asteroid belts in, and the ships do slow down whenever they're doing something inside said asteroid belts. There's at least one episode I can find with a 15 second bit of searching where an asteroid hits and causes significant damage to a federation starship, although it is significantly smaller than the enterprise, which is huge.
The next obvious arguement is "well space is 3d, why don't they go around?" Ok, but wouldn't that be slower than going straight through? Pretty much the same game effect as just slowing down a bit.
Either way, it's an abstraction that allows for functional, plausible space terrain. Without asteroid belts the number of large system-encircling things you can successfully hide in, or use your enhanced terrain navigation skills to pass through quicker than an opponent, or generally -interact- with is one lower, and given how many systems have asteroid belts it's a -big- one.
Sadly I can't answer your
actual question solidly in either direction, making me somewhat unsure I should post this reply in the first place, because clearly your opinion about asteroid collisions and my opinion is very different to start with and given it's a fictional situation in a game with many layers of abstraction there's not really much productive debate that can be had, it's all so subjective... But still, these are the reasons I think it's fine.
It doesn't
sound like asteroid collision can currently be turned off, though investigating the AsteroidBeltTerrainPlugin.java does sound like the obvious starting point. So to try and add a bit of value to my post, I investigated it myself. It's been ages since I did any solid starsector modding, but if one can override AsteroidBeltTerrainPlugin.java then there's a line on line 179
suggesting that even though it calculates the changes of collision from the size of the fleet, it then ignores that and sets the collision chance to 50%. If that were set to, say, 0%, I think that would do what you want. Again, can't confirm as it's been a while and I can't remember how difficult overriding such a plugin is, but I'm reasonably sure it's possible... so it now sounds like it -is- possible to reduce the chance. If you wanted to learn modding, this would be a very simple starting point, and it certainly sounds like you have the motivation needed!