Were there ever heavyweight non modernized versions where the roof style would be represented?
Yes, certainly on B&O, at least. About 1940, the B&O "stream-styled" heavyweight cars for several name trains. The round roofs were done in either this sloped style or the straight-to-the-end style, but the windows looked the same as on a standard heavyweight.
On B&O, the fixed steps were also replaced with fold-up steps at that time, but I think other roads stayed with the fixed steps and this roof style. (Which, from a modeling standpoint, means that it is easier to start with an MTL coach or a Rivarossi coach, respectively, for fixed or fold-up steps.)
Into the 1950s, most of those cars eventually got modernized Thermopane windows. So, it is a matter of modeling era what fits on any particular layout.