Stephen, I think you've hit the nail on the head; the "K.I.S.S." ("keep it simple, stupid") principle, as it is called in engineering. I can understand exactly what you've said, as a result of having built two splayed carriages at 1:12 and 1:17 scale, and I encountered those various difficulties. Whether hand-made or produced by machinery, the parallel brackets would indeed make it much easier to produce, which makes a big difference when large numbers are required.

The reference to the coffret I do not understand; why would a chest need a splayed rather than parallel bracket? I do understand that carrying the heavy chest on the brackets does add awkwardness to overall handling.

Thanks very much,

Regards, John