This is a bundle, not an integrated solution. I have some of those Devolo Homeplug devices, and whilst they work well, they are heavy and bulky.

A proper integrated solution would stick the powerline electronics inside the box, and use a normal plug to provide both power and connectivity with a single cable.

Come on Devolo, sort it out.

These are becoming de facto by stealth,

In reality they are unlicensed transmitters, getting CE mark under the wrong regulations. Mains wiring is not shielded, screened, coaxial or twisted pair. These things radiate a huge amount of RF outside the home destroying MF & HF reception of analogue and newer DRM services.

For people too lazy or mean to run CAT5 cable in many cases.

The Wifi/Switch box does have the Powerline electronics inside the box, and uses a bog-standard figure-8 mains lead.

The Ethernet-Powerline adapter has no "box" into which to put said electronics, hence the wall-wart styling.

I live in a listed building, with walls upto 18" thick, I can't run cables and wirless is only good from room to room, these things are brilliant.

"For people too lazy or mean to run CAT5 cable"

Or those people who live/work in buildings which were built at a time when the construction material was brick and/or stone rather than snot and sawdust.

Never underestimate the attenuation properties of a couple of good, solid courses of brickwork.

Yes there are occassions where this is needed because WiFi won't work or cables are difficult.

I alluded to that in the OP.

But we do need proper standards testing of these, which doesn't exist. At the end of the day if the designers can't make them work correctly then we need a different solution. The Radio Spectrum is assigned and protected by National laws and International treaty.

It may be that these need an allocated band. Or limited to the difficult buildings (which often block the transmissions from leaving the building).

Most people don't need them. They do pollute the Spectrum, especially some models/makes. Since some are much worse than others it suggests the correct standards and testing is not getting applied.