This is a good question! Especially because I think I might have a hypothesis! Tell me what you think.
When I was on vacation in the Adirondack Mountains in New York I went to a mountain museum on a lake. The museum showed old photographs. In the winters, the owners cut big elongated cubes of ice and transported the blocks by horse through the snow to underground shelters near New York City for rich people to use in their ice boxes to keep their food cold. [Even less than 100 years ago, there were no refrigerators. It is hard to believe, isn't it?]
Ice was a status symbol. To have an ice box in your home, for restaurants to have ice in their drinks, this was a big deal! A lot of work went into getting ice into the ice box, and especially, it was prestigious to have ice during the summers. It came from the underground shelters. In the ugly New York summer heat, putting ice in a person's drink was an act of kindness! My guess is that this long time ago, ice caught on as a status symbol and it eventually trickled down into people's lives and became habitual.
What do you think? Do you like this idea?