I don't think they could. I think you are picturing the situation as one where the plane has little no forward motion and it is just descending, with the belly of the plane parallel to the ground - like a skydiver with arms and legs outstretched and facing the ground.
Planes don't generally fall from 30,000 feet. Most incidents are closer to the ground - wind shear on landing, icing during takeff, collisions. So you really are trying to protect against an emergency in flight. It would have to be a situation where there is no chance of landing safely. All of the engines become disabled and no hope of restarting them or one of the wings falls off by itself (perhaps due to flaws your wing ejection system - adding that system provides an opportunity for it to fail).
So the plane is traveling along and there is an emergency mid-flight. Somehow, the pillot has to slow the plane down so that the chutes don't get ripped off or flattened out/twisted and unable to inflate. If the plane is already plummeting to the ground then it won't work. Your wing ejection system would have to be explosive to propel the wings away from the cabin, otherwise they wil just fold back and crash into the cabin. The explosives would have to be strong enough to do that but not so strong that they put a hole in the cabin.
But maybe you can get the plane to stall, pop off the wings, pop out the chutes, and you have a sky-diving airplane tube still accelerating to the ground. The chutes would have to be big enough to get the thing to the ground. But still small enough for the plane to have taken off in the first place (okay, ejecting the wings helps to reduce the work of the chutes, but still).
I think that quick-inflating helium balloons might work better than chutes. Compressed gas tanks would take up less space than the chutes. Sudden decompression of the tanks would speed the inflation of the balloons. Or maybe use both - have helium inflate the chutes.
But the answer to your question is the same as the answer to why people don't go around in space suits during flu season.