The reason for tiny windows is more technical. Windows are weak, expensive, offer poor insulation, privacy and security. Modern techniques mitigate this problem

The reason for tiny windows is more technical. Windows are weak, expensive, offer poor insulation, privacy and security. Modern techniques mitigate this problem: better structure allows for less reliance on walls for support and therefore more room for windows, mass production make them cheaper, double pane glass improve insulation, security and privacy can be dealt with large motorized rolling shutters. I don't believe the lack of sunlight is the reason for vivid colors of the past. If anything, the colors were darker, though more saturated. Also, while tiny windows did not allow for a lot of sunlight, it is the opposite at night, where modern lighting is much brighter thanks to cheap, powerful and efficient LEDs. Here, I think it is just fashion, nothing technical.