Original Tribes' chaingun was mostly a throwaway/finishing weapon. Majority of the game revolved around projectiles you could actually SEE travel, and thus evade, and that's part of what made it special.
I wouldn't go that far. The chaingun in T1 just required more skill to be effective. You needed to fire in rapid but short bursts and lead your aim. Conversely, in T:A, you just hold down the trigger and keep your reticule on the target.
Another thing they can do is reduce the damage of the rapid-fire projectiles over distance. This would make them considerably less effective at long range.