Deadliest Warrior, did Pirate Vs Knight, where you can see, Firearms of the time, vs Armor of the time. Catch it on Spike.com .
Now, as a Trained firearm person, at bot the military and competitive levels, I can tell you this. Any Idiot, can kill someone with a gun. Any idiot, can also kill you with a stick, or a rock. But untrained idiots, Kill themselves with guns far more often then they do the other person they want to kill.
This is ESPECIALLY true in black power (we had an incident during the last black powder season here, with rookie retards). So while yes, you needed LESS innate ability to use a gun, you still need the training, to be a competent user of it as a weapon.
So it costs a feat. And exotic makes sense as the feat for it as well because that's where it's "niche" is. Can't fault the issue of having to burn a feat for it, just because Bioware didn't understand how weapon proficiencies work in DnD. Even in PnP it's Exotic unless coming from a culture where it's standardized, in which case it becomes Martial. And just because it's Martial didn't make it easy to learn, unless you were one of the classes that got ALL martial weapons as a class feature (fighter etc). Otherwise, everyone else. One Feat One Weapon.
~Rex