It could be a result of less diversity of thought, or critical thinking, over time. The more people rely on things for answers, the less they reason or come to their own conclusions. The culmination of mass media around the globe, ‘google it’, ‘tell me ai’ etc. So their brain says ok, I’m content with fewer colors and those that are less vibrant. Because the brain is being used less and not as vibrantly, in terms of neuron utilization. Just a thought.