And a width of 21mm is the only configuration that could satisfy this requirement?

Precisely that, and no other? I don't mean to be flip, but it beggars belief to say that this is some sort of platonic form of tablet connector, especially given that the connector originated on the iPod in 2003, and existed not for stability, but for thinness, and to provide additional pins for accessories in a larger Apple-specific ecosystem. It was designed with a purpose, no part of which beyond thinness obtains when applied to a non-Apple device.

I am sure they did not copy the 21mm because it looks the best. There must be some other reason.

> I am sure they did not copy the 21mm because it looks the best. There must be some other reason.

We agree. That reason being, it looks like Apple's, and consumers love that.

No, the reason it's that wide is because that's how wide PDMI cables are. They are all about the same width. It's a standard.

It's probably because these are easy to buy. The people making $1 iPod replacement cables must buy them somewhere, after all.

I have a Sansa music player that uses an iPod cable but with the wires hooked up differently for no apparent reason. It seems to be a pretty common thing.

Maybe the component supplier put in a cheaper bid if the part sizes were identical?