I've wondered the same thing, mostly about 4x5 and mostly because it's half the price of everything else (or, a foma100 50 sheet box is the same price as a 25 sheet box of FP4).
What do you mean by "vintage look", is it just larger grain? Or some unmeasurable 'look'? If I go a box of 4x5 100 I'd be devving in Rodinal, would that help with whatever 'vintageness' it has?