Mistress BlackDiamoond wanted to make sure that this guy would never mess with her and that he would never ignore her. She had to do it because she felt that he did not know how to do things the way she wanted them to be done. That is why she had to make sure that the guy licked her feet and that he endured being trampled by her high heels.
Mistress BlackDiamoond was not in the mood to mess around. She felt that she had to punish this loser and that is what she did at the end of the day. The mistress took out her sandals and she used them as a weapon to punish this loser. He had to endure being trampled by them and when she was done doing so, she made him lick them as well.
Mistress BlackDiamoond wanted to try some naughty stuff but she was not ready to use her pussy to do it. So she chose to use her feet to do them so that she could get a feel of whether it was worth it for her to use her pussy for the same stuff. The mistress enjoyed herself so much that she knew she had to try those things with her pussy.