Unless a pattern movement includes a stomp on the opponent's foot or leg, stomping the feet during pattern movements is useless and is usually detrimental to getting a high score. Some people may think it sounds cool and may increase their scores, but it does not. Some may think it increases power, but it does not. Baseball players do not stomp as they swing the bat, golfers do no stomp as they drive, and boxers do not stomp as they punch.
When teaching beginners, to emphasize making good hand and foot timing, my instructor stomps the stepping foot to illustrate how the foot and hand should reach the end of their movements at the same time. The problem is that sometimes the students think that the stomp is a part of the movement, so they start stomping all the time. It is always more difficult to get students to stop doing something than it is to get them to start doing something, so sometimes this stomping habit is hard to break.
When moving in a pattern or in the street, the feet should silently sweep over the floor. In the street, they are clearing a path though street trash seeking firm ground.