my mothers filter flo only had two wash temps, all warm rinses....if you wanted cold, you had to turn the hot faucet off.....
BOL of the line was one thing, but for that time frame, many people were switching from wringers, where a warm rinse was the norm, not so much for the clothing, but for plunging your hands into the rinse tub, warmer temps were preferred...
cold was probably more effective or energy savings, but theres a certain feel to clothing after a warm rinse.....also added softness to the clothing if hung on a line....
water levels were not a big concern then either, just like a wringer, if your going to go through the trouble of washing, you were doing full loads....but things changed as time went on and a new generation came in, automatics that you could wash and dry, any day or night, and at your convenience....it was all about flexability.....
so much has been lost from times past.....especially long, slow, simmered meals prepared on the stove...the smell of detergents while washing clothes, open windows for fresh Springtime air.....well, at least we still keep it alive