2 parts, walls should be easier to open and close, that's the major point

Secondly a minor addition, if there were a standard for junctions of power cables, so they could easily be added to, that would be nice.

Then installing a socket would be: open wall, connect socket you just bought with standard junction connectors, close wall. $50

Rather than: cut a load of holes in walls, connect socket using annoying wiring techniques, fill in holes you made, plaster and repaint so that next time it'll cost all that money again. >>>$50