Because people liked the feature. Look, I'm just saying WHY they added windows. That was the reason. I'm not saying it's a good reason or no one could figure things out before. They added them for that reason, people liked it, and it stuck around. Yet, there's always gonna be someone dragging out their 30 year old washer going "but mine is fine!". Never said it wasn't. Or someone pointing out that not all washers have a window even today. Cool. Nifty. But if yours does have one, that was the reason they got added.