Can anyone explain to me why the dart gun in SR4A require exotic weapon training in order to use? to me it makes no sense, a dart pistol to me seems closer to a regular pistol that say a taser. It seem to me that while all the other exotic ranged weapons make sense since they are not fire in the same way that other weapons are the dart guns seem out of place and would more appropriately fit into the long arms and pistol group respectively. does anyone else agree with this assessment?

A dart gun would be closer to a crossbow. The larger, heavier ammunition requires more attention to trajectory than just simple aiming. That said, I agree that a dart gun and a taser should be in the same category. The taser specifies that is fires electrified darts. With your reasoning, I'd allow Pistols (taser) and Pistols (dart gun) to be interchangeable.

Really, that's an argument for Taser to be Exotic. And an even stronger argument for revamping the Firearms skills, but that's another thread.