Why do some British people hate the royal family.?

I'm American and don't know a lot about the royal family but I heard some British people want to end the monarchy and have a republic. I like Prince William and Diana was wonderful. As for the rest they are o.k. They are not perfect but people shouldn't have such a beef with them. If people feel like they aren't doing enough in the government Parliment should just give them a little more power. Just make sure they don't abuse it. In America the president has a lot of power but can't abuse it a lot due to checks and balances. I don't think it is fair just to kick them out into the street.