Re: Plug cable entry angle
"But if it's safe, why not have the 13 A fuse in the socket, and save all those bulky and expensive plugs? And if it isn't safe, the basic design that allows such easy substitution is flawed. Either way we should stop congratulating ourselves."
Consider this. Most fused solutions are open to abuse, as well as unplanned outages (no replacement fuse available). Drop fuses entirely and go to breakers.
Put the breakers in a panel, and pull wires to each socket or socket pair, depending on location.. At that point you are not just protecting the power cord for the device, but the entire circuit. I am all in favour of protecting wires in the walls where I can't see the smoke.
That also makes the power draw sufficiently distributed that the number of devices in a room is unlikely to be an issue - you can freely plug things in, and the loads all go back to the breaker panel independently. As long as you don't trip the building breaker, you are fine... if you do, re-planning is in order.