Vision, vision length and vision cones were brought up more than once during the development of X1. I believe the underlying reason it's brought up is all to do with what battlefield information the player has access to. The relatively short vision range with the relatively tight vision cone restricts what the player knows at any time. This is especially acute at the start of any fight as all the player's information points are clustered together in one place, whereas the AI adversary information points are dotted around the map, so the AI has a much more complete picture than the player has.
Does having incomplete and restricted information about the battlefield add or subtract from gameplay? One might argue that the more complete a picture a player has, the better that player can formulate strategies. There are certainly plenty of games that present all the information to the player. Incomplete and restricted information then frustrates a player because they don't know what's going on. Equally, one might argue that an incomplete picture can mean the player can be surprised by the AI's actions, and the player can in turn surprise the AI - ambushes are only effective if there are gaps in information that can be exploited, and it is entirely possible in X2 to run around an enemy group and flank them.
If having incomplete information is a beneficial asset to gameplay, how much and to what degree should that information be restricted? E.G. how far and how wide should vision cones be?