That's actually a damn good question and one I've never thought about until now!
We've had remote switches around for cameras for years. This gives people the chance to shoot photographs of all sorts of stuff, even something like a lightning bolt. If they had to hold the camera in the traditional fashion and release the shutter by depressing the button, they'd really struggle with such shots. But the remote makes it easy.
If we can use a remote device with a camera, you'd think we could do the same for guns. We might need electronic ignition, but that is now in the works. Even if it's more expensive, it's not like snipers use a tremendous amount of ammo anyway, especially when compared to the usual infantry tools like M-16's and machine guns.
Heck, with modern technology, we could mount a gun to the top of a pole, the upper floor of a building or in a tree, slap a Beta mag in it and control it from a few hundred yards away if we chose to do so. Such a device would be cool to have in Iraq right now. You could set it up where you wanted it beforehand, and with the use of some cool gadgets, control it and take out lots of badguys without ever being in the danger zone.