Mystery Machine

I've been meaning to put this question to a recording engineer for a while, but my mind always seems to go blank whenever one's around. It's a problem I'm working on, but in the meantime I figured I'd address my question to the blogosphere. Thinking caps on? Good, here goes:
Why do most recordings of string quartets arrange the sound of the instruments backwards so that the violins emerge from the right speaker while the cello and viola play through the left? Why not make it sound like it does in real life, where the instruments run, from left to right, violin, violin, cello, viola (or sometimes vn, vn, va, c)? It's weird.
I expect some good answers and, if possible, at least one plausible one. A prize of some sort may or may not be awarded.