Reading between the lines of your post I do understand your argument. A monarchy underpins class discrimination, all societies have socio-economic classes, monarchs tend to make them more visible.
During the Middle Ages, in England, as in most of Europe, the feudal system was the dominant social and economic system. Under the feudal system, the monarch would grant land to the monarch’s loyal subjects in exchange for the subject’s loyalty and military service when called by the monarch. Besides grants of land, these subjects were usually given titles that implied nobility and rank, such as Duke, Earl, Baron, and so on, which were passed down through the holder’s male line.
Imperial titles and rank still persist to this day and will go on doing so whilst we have a monarch. That said, there is a considerable minority in our country that finds both monarchy and the class system unpalatable, but most of us are realists. The Monarchy is a huge tourist draw, there's many a diehard republic supporter in the crowds that enjoy the pomp and processions that is such a spectacle of a Monarchy.
The Princess of Wales was once simply known as Kate Middleton, from a middle class family, just as Prince William's mother was Diana Spencer, although her family were much higher up the pecking order. The fact that having a Monarchy underpins a class system doesn't bother the majority of British people, so for those of us who would prefer our system classless, it's best really to shut up and put up, because it's against the flow and it ain't going to happen.