Well, for one thing, moving the camera around might also drag the HUD with it. That would create more of a flying/moving on rails effect than a full 3D camera. Also, your player model may not be visible to yourself. So, zooming back might show a gun floating where the player's camera view used to be. I can image a few other obstacles from a programmer's perspective.
I'm not going to have cow over it, although from a designer's perspective I think I would have tried to build that capability in from the beginning.
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TAZ
[edit for clarity]
"Do you think it is wise to provoke him?" "It's what I do." -- Stargate SG-1