In addition to the other arguments mentioned about the clothing, one more thing: colour photographs, and indeed any photographs, all that survives from the time

In addition to the other arguments mentioned about the clothing, one more thing: colour photographs, and indeed any photographs, all that survives from the time, were very, very uncommon, so you'd take out your best clothes for the occasion. You won't know what the peasants wore their entire life except for the day the official Tsar's photographer visited. Today, people dress nicer for important and/or rare pictures (weddings, official portraits, etc) than for point and shoot pictures at the park.