One of the first things that you are taught as a child in the U.S. is that royalty is tyranny. There is no voice of the people when there is royalty. Now I'm aware that the U.K. is a constitutional monarchy but having a Royal family still costs British tax payers a lot of money. When I was here five years ago there was a news article about how each British Citizen had to pay £0.70 to support the Royal family. I've asked friends about this, and their answer is that it is good for tourism. You can't get rid of a Royal family and then bring them back if you decided you liked having them around. So the U.K. has one of the few Royal families left and use it as tourist attraction. (I just know that any museums or sites owned by the royal family, like castles are the ones that have the outrageous admission prices.)
As far as the government side, I understand that having the royal family around to entertain visiting heads of state. (The U.S. doesn't have this department so the President pulls double duty.) But it was also explained to me that royalty thinks long term since they want to see their children be in power after them, where as a politician will say and do anything to get re-elected the next term. The thinking for the House of Lords, that appointed instead of voted in, is that since they see after trades, if they are appointed then they do not have favors owed to any companies.
But I still think it is weird that I will be getting the day off for the wedding in April when the prince gets married.