The OP is correct in his original assessment. I too, have a home which first saw electric in the 50's and the old boxes in the wall were small (imagine the screw for the outlet running on the outer edge of the box, not the inner).
Since I've purchased the place, those have all been ripped out and replaced with the biggest metal boxes I could find.
On another tangent, I've also replaced all the aluminum wiring, the service panel and put an outlet every 4 (yes, four) feet.
Guess they weren't planning on any X10 devices in the 50's.