there's a "filter" in front of the raptor turret view, which largely limits visibility. It seems to be designed to handicap that weapon. Now 3rd person would sorta defeat that (with certain trade offs).
honestly I think it's fair to limit the gunner to 1st person. u2xmp was done that way for a reason, and I agree with it.
If I may go a little OT here. It seems a lot of people ask for "improvements" that would benefit certain players, which in turn makes it harder on these players' opponents; i.e. disturbing the balance.
Case in point: if aiming the turrets was easier, the chances of the car winning a duel against a pair of "pedestrians" is greater, because of the added firepower. Not to mention the fact that the passengers can get out anytime unscratched. But before you ask for that change, think of yourself as a pedestrian, instead of a passenger of the car. Would you still want it? Do you think it's fair to give the car more advantage than they have now? Is it better to follow the ways of UT2K4 instead of U2XMP?