This applies to the later boxes and is to do with 'marketing the
product'.  The movements cost less but the box gave the impression
of something more expensive.

However, just as some of the larger movements can have unattractive
arrangements, some of these 'large boxes with small movements' can
be surprisingly good in terms of musical quality, tune arrangement,
etc.  The best test is to use the ears first and then the eyes!

One advantage, probably not intended, is that a larger box can give
a better acoustic response (due to the larger base board) than if
the movement was in a smaller case.  In fact, small boxes, particularly
the miniature boxes and snuff boxes, can give remarkable performances
when placed on a good resonating surface. The surface acts as a
soundboard and can compensate for the inadequacies of its own case.
Often an upturned drawer will give the desired effect when
demonstrating a small instrument.

Paul Bellamy