The peak of easy-practical-and-no-longer-remotely-fashionable would, I think, be the Ancient Greek chiton. On the one hand, really simple: it''s a tube, partially stitched up along one end. One-size-fits-all to within a reasonable estimation of your height, extremely simple to make, no wasted fabric in off-cuts, just pull it over your head and tie it in at the waist with a belt or something.

On the other hand... no.