I agree that it seems inappropriate to preserve order. That seems an
inappropriate imposition, inconsistent with what SQL does elsewhere.
If there is a natural sequence (e.g. - a value assigned by nextval()), that
offers a natural place to apply the usual order-imposing ORDER BY that we
are expected to use elsewhere.
I suppose it is troublesome if there is no such natural sequence, but I
wouldn't think it too meaningful to expect order without some visible
source of order.