Kinda hard to shoot with the gun collapsed into the stock, but you can still shoot with the stock collapsed or folded on an AK. Usability > form.
I will admit that the idea of a more easily packable firearm for emergency use is neat. A cousin of mine had a M6 survival gun with the .22 hornet & .410 shotty barrels under/over; that was an awesome little firearm. I still remember being surprised by the perceived power of the hornet. http://en.wikipedia.org/wiki/M6_Aircrew_Survival_Weapon