Because thematically it makes sense for Missiles and Torps, the only secondary weapons available at launch. Missiles and Torps have guidance systems and are solid projectiles that won't diminish in power at range and won't be less accurate at range.

Sorry, but Missiles and Turrets were released in the same wave, which was Wave 1 (TIE Advanced and Y-Wing).

And maybe that's actually why it is the way it is. The only turret available during wave 1 was the Ion turret. Maybe they wanted to avoid the range 1 4 dice Ion attack. And since the ion turret is range 1-2, the lack of range 3 defense bonus was only impacting the missiles and torpedoes.

That all seems to be making the bizarre assumption that they weren't planning on ever releasing anything ever again for the game. Also, that an Ion Turret attack with 4 dice is somehow overwhelmingly powerful... Anyway, the real reason the rules are as they are (the same for all Secondary Weapons) has already been mentioned in this thread: Simplicity.

Heh, since we were not part of the designing team, assumption is all that we can make. Just like saying that the real reason is for simplicity is in fact, an assumption. That's also what I think, but we can't be sure.

I'm pretty sure that I read somewhere that the designer never thought the game would catch up that much. Maybe they didn't really planned ahead at first. They just knew that they would do at least the ship from the OT and that's it..

Well, FFG did double of their best case expectations for the release. Which was way, way, way, way, way under what the demand was.

At first (Core Wave 1) it was good for secondary weapons as most of them were range 2-3 all were discarded and it gives some semblance of being a long range tracking munitions where you don't get the extra chance to evade unlike laser blasts. However for simplicity sake it has applied to all secondary weapons to include cannon and turret slots. Not all torpedo and missile upgrades are secondary weapons. Also as far as rules go there is no such thing as munitions. It is just a word that appears on the title of a couple of upgrade cards as well as the title of a damage card from the old core set.

things like cluster missiles and prockets don't need any range bonuses, and it keeps the game simple.