I'm curious which company started using the standard 0.1 in (2.54 mm) pin pitch for components. This is surprisingly difficult to Google. I see 1956 and Cicoil Corporation when it comes to ribbon cables but I doubt this was the first use.
On one hand, a tenth of an inch is kind of an obvious measurement to use, speaking as an American. On the other hand, I suspect that the choice had just as much to do with the manufacturing capability of "the time" (whatever "the time" was). For example, now we also have pins twice as dense (0.05 in), but the legacy of the original choice remains.