Probably because the old ones were not good. Mine had voids in the steel that were filled with body filler and painted over. Despite that, mine is heavy and if I can get something up on the bench to clamp it, it's not going anywhere and will hold equal to anything.
The newer bench vises are better made but a little lighter. There seems to be little to no body filler but you can't tell for sure till you pound on one. An old American made vise would look better to the American eye but I don't think it would hold any better. The HF one is made of good enough steel, has good clamping force and looks OK. The jaws I saw closed tight and even. I'd prefer an older vise but I would not be afraid to buy a new HF one with a coupon or on a super sale.