Not always just random maneuvers, there's also a technique where you "chase the splashes," in order to throw off the aim. The enemy will be adjusting their fire based on where their last shot landed
I thought it was to buy time more than avoid getting hit altogether. They either have a targeting computer or, when that is down, they are "locking on" manually. Seems like, especially between two comparable ships, making it take 12 seconds to track and hit you rather than say, 3, would be an advantage. I think somebody else mentioned it above. The "shots not fired" factor.