George Lucas actually said that Star Wars ships were actually envisioned to fight like age of sail battleships, ie, sailing (or flying) at close range to each other and exchanging broadsides... actually very like we see in both The Return of Jedi and the Revenge of the Sith.
...although, curiously, not here - all ships we have data for, at the moment, has slightly more attacks forward than to the broadsides.
I'm not an expert on naval warfare, but it occurs to me that if you approach at an angle rather than flat from the side, you can bring all your guns to bear on an enemy while reducing your own target profile as much as possible, making you harder to hit.
Approaching from an angle also seems at first glance the best way to fire all your ship's weapons in Armada.