I agree that this is probably a major contributor. The human mind has only so much mental bandwidth available, and mere existence in modern society demands much

I agree that this is probably a major contributor. The human mind has only so much mental bandwidth available, and mere existence in modern society demands much of it. Whatever is left over is slowly consumed as responsibilities accumulate. I believe that this loss is somewhat reversible, however. Whenever I take a vacation that serves as a hard break from practically all of my responsibilities, I notice that the color and details of the world begin to trickle back in. If only it were practical to remain in that state for extended periods.