jbeale wrote:Is it better if you separate the power supply and the cable? There are lots of 5V USB power supplies, and the USB port <-> microUSB cable is also widely available.
There are two points here. Do you understand the difference between a charger, a power supply, and a regulated power supply (I'm not suggesting you don't but you can't claim that a particular device is suitable without testing a representative sample of a particular device. The one you have may work for you but the same make/model may not work for someone else.)
The cable is a much simpler business. All wires have resistance and this resistance causes a voltage drop. A thinner wire has more resistance, also the resistance is proportional to length. A long thin wire will have a significantly larger voltage drop than a short fat one. In my experience the lead to the mains is fine but the output wire is miles too long and adds to the nest of wires effect. You could open up the device and shorten the supply wire. If you do that and all you find inside is a transformer and a thermal fuse then it's an unregulated power supply. These have wide variability. They probably only cost 50 cents to manufacture.
I note from your picture that it is a model for the US market and plugs directly into the socket so the best you can do is use a high quality short USB lead.
If there are plenty of MicroUSB supplies there must be a hundred times more 12v discarded wall warts that don't have a use, or a MicroUSB outlet. The spirit of RPi is to re use equipment. It defeats the object if you have to go out and buy peripherals. If you have to buy a power supply, a keyboard, a mouse and TV then it's cheaper to buy a refurbished laptop if all you want to do is Python programming.