The upper class wanted to publicly differentiate themselves from the peasantry and yeoman classes. You couldn't easily do it with displays of wealth (since the

The upper class wanted to publicly differentiate themselves from the peasantry and yeoman classes. You couldn't easily do it with displays of wealth (since the town yeomanry were often well-off even if they lacked titles), so they did it by making it illegal for commoners to do stuff. Like have dovecotes, or wear certain colours.