For the purposes of making a Tremulous-related video, mechanima, trailer, promo, etc. the 3rd-person view has its obvious uses, as you would not be then in a "game" situation, but instead making a "film".
It is a cool ability in games where people don't consider it a cheat, but that's usually because, in those games, it confers almost no advantage. I liked it in games like Tribes, where one piece of gear (their damnable version of a "jetpack") had a steep learning curve, but was an essential element of the game, while the interface was also somewhat counter-intuitive (it had its own brand of physics, quite unlike Quake or Unreal or even Half-Life or DX). But you really didn't get any better view, and you were constantly toggling views in that game anyways, what with the command screen, a compass, waypoints, and the like.
It should stay cheat-protected in Tremulous.