What type of windmill of old? They look like a scaled up Jacobs wind system from the 1920s. No surprise, Jacob's wind got a lot of things right back then.

If you mean the old water pumps used in the American west (they are still made today!), those are good for water pumping because they produce high torque in low winds, but they make less horsepower and that is what we care about.

If you mean the Dutch style windmills/houses, we could do that, but the big house blocks a lot of wind and so it is not efficient.

I can't think of any other style of old windmill. However if you can the answer to your question is likely because that style is much less efficient.