Blaster launcher in XCOM was extremely dangerous, especially in hands of aliens (have got all my marines killed in first turn by it more than once). Not like that, IMO it was too dangerous and took some of the challenge away.
If added, maybe ammunition could be kind of very fast remote-controlled plane more than rocket or missile with a lot of TU:s, but not infinite so that you could not shoot it around many twists at once. Make turns cost a lot of TU:s. High, but limited range, explodes immediately if shooter gets killed or stunned. Can be shot down by aliens (or you) in mid-flight. Launcher and ammo costs very high (just like real world guided missiles vs rockets). Also controlling it should take all TU:s from the shooter, so he can't do anything else while it is in flight.
Too complex?