According to this Wikipedia article, the practice of outdoor lighting displays didn't widely begin until the mid 1950's-

"the tradition of decorating evergreen trees with Christmas lights dates back to 1956 when the McAdenville Men's Club conceived of the idea of decorating a few trees around the McAdenville Community Center."[6] However, the The Tree at Rockefeller Center has had "lights" since 1931, but did not have real electric lights until 1956.[7] Furthermore, Philadelphia's Christmas Light Show and Disney's Christmas Tree also began in 1956.[8][9] Though General Electric sponsored community lighting competitions during the 1920s, it would take until the mid 1950s for the use of such lights to be adopted by average households."

I never really gave it much thought. If my mother were still alive I'd ask her what they thought when people started doing that. It must have been a big deal. Remember piling into the car to drive around and look at Christmas lights?