Looks like a mechanical problem waiting to cost you more money.
* Winding means sliding contacts to transfer the power... when they wear and ultimately fail, the failure mode is often overheating due to higher resistance. Now you have heat in a confined space (wall) with poor access. If you call the fire department to make sure there is no fire along with the smoke, they will make sure, which is a good thing, but it won't be pretty.
* The spool must have a spring rewind mechanism... again, rewind mechanisms tend to fail and now you have a cord that won't go back out of sight.
Yes, problematic. I guess though that if the box in which the wire is rolled can be fully pulled out of the wall (after unscrewing of course) then maybe these problems won't be so bad.
It doesn't seem easily replaceable (or even inspectable for damage)
It's not portable / it's fixed to that particular socket. So, if I occasionally need an extension cord in the garage and in the den I need to buy two of these instead of only on cord.
It's more complex, almost guranteed to be more expensive and more prone to break down.
Winding a cord that tightly probably damages it unless it's specially constructed.
Doesn't look like it can be all that long. 50',75',100' ext cords are common.
While I like the idea, when building a cord into the wall, it should be of a gauge that can support the maximum current of the breaker installed. I don't know what European plugs are (pictured), but US ones are typically 20 amps. It takes a minimum of a 12-gauge electrical cord for that and the pictured cord looks like 16-gauge at best.
US household current is 110V, 60Hz and typically 15 or 20 amps on a circuit. 16 gauge is approximately equivalent to a 1.5mm^2 cross-section solid wire, or to 30/0.25 (which I assume means 30 0.25 mm^2 strands).
I rarely need an extension cord for any purpose, and I rarely need it in the same place. Part of the appeal of an extension cord is that it is modular and mobile. With these plugs, I would have to replace every socket in my home. With an extension cord, I need only one. It also comes with me when I move. This is a fix in need of a problem.
Seems like two changes could hit many of the concerns here:
(1) The box can unclip from the wall, and disconnect from an internal fixed plug. An emergency pull handle is all you really need.
(2) A slow-but-steady retract mechanism. grinich's idea for a small electric winch makes a lot of sense if a spring version couldn't do it slowly and steadily enough.
And if you're worried a moron won't listen to your amperage ratings, a built-in breaker.
Still, a nice-to-have in the kitchen, workshop, and garage. The electric knife we use at thanksgiving has a uselessly short cord, and nobody remembers to find a good extension until way too late in the evening -- too many other concerns first!
If this is using a spring-loaded rewind, it's potentially dangerous.
One of the kids in my school up was blind in one eye (it looked terrible). He was next to one of those vacuum cleaners with a retractable cord and the end of the cord flew up and hit his eye when his mother was winding up the cord.
I'm pretty sure they don't allow spring-loaded rewind cords on vacuum cleaners any more.
I've seen similar concepts before, but they never actually make it into production. There's too many things wrong with this, not least of which the costs to manufacture and install.
Also remember that tightly coiled power cables carrying significant load will heat up and could cause a fire.
Smart? Eh I dunno... don't install it on your outside walls or you won't feel too smart when your heating bill arrives. Insulation in wall keep warm in? That's umpossible!
* Winding means sliding contacts to transfer the power... when they wear and ultimately fail, the failure mode is often overheating due to higher resistance. Now you have heat in a confined space (wall) with poor access. If you call the fire department to make sure there is no fire along with the smoke, they will make sure, which is a good thing, but it won't be pretty.
* The spool must have a spring rewind mechanism... again, rewind mechanisms tend to fail and now you have a cord that won't go back out of sight.