With the onset of the twentieth century, artists and thinkers began to discuss concepts of attire... ideas of blending-in versus standing-out. One belief was that everyone should dress alike socially - relegating self-expression to the home environment. Taking that thought further, there were also experiments in having attire match decorative motifs within the home.
I like the concept of matching attire and home furnishings... which seems - harmonious and consistent. This would require a clearly-established and committed sense of self, I think - to align oneself with a particular style and stick to it.
Now returning to the concept of dressing uniformly within a group - we see this quite often... teams dress alike, people dress rather regionally, and to some extent - even people asserting their sense of self-expression sometimes achieve similar end-results. Dressing for formal occasions, men - more often than women - tend to have a unified appearance.
From a hotel window my husband and I recently observed an odd example of uniform dress... herds of young women in towering heels and tiny bandage-tight dresses teetering, trotting, and stumbling along the sidewalk on their way to and from the clubs.
But today - because it's a wintry fall day - chilly, rainy - grey and green... and there's more of the rain and cold and grey to come... I decided to try this: when the weather is dull and overcast, I plan to wear one little cheerfully bright accent - a sunny yellow scarf or hot pink lipstick or red socks... just for the happy effect it might produce in other people. Then, when it's sunny and bright - perhaps the rest of the crowd needs to see a bit of cool blue, or might benefit from a minty fragrance passing by.