Why did the Empire BAN Colored Clone Trooper Armor After Order 66?
During the Clone Wars, the Clone Troopers of the Republic would often trim and paint their armor with various colorings and symbols as a way of expressing themselves and bonding with their brothers. Unfortunately however, after Palpatine declared the creation of the galactic empire colored armor and all markings were outright banned for the Remaining Clone Troopers.
Palpatine did this to remove all sense of individuality among the clone troopers, as well as because it was originally permitted by the Jedi Order, which were now traitors to the galaxy. He was worried that the paintings would remind the Troopers of the Jedi Order and instead demanded that they be loyal to only him and his new empire.
The bland and uniform new armor style was also intended to strike menacing fear into the general public so that Palpatine could rule the galaxy with an iron fist.