If you look at a very broad range of years, you kinda start to notice regionalism going in and out of fashion... well, until the regional fashions stopped keeping up. Seems nostalgia had something to do with that, but I figure it is only a matter of time before some fashion designer plays on regional dress and makes it fashionable again.
and yes, I strongly agree that the working classes had some interest in fashion and this is why I so love those paintings! You can see influence directly yet so many peculiarities :)