To be honest, I've avoided them as much as possible, therefore I probably shouldn't even be responding, however ...
They represent the phenomenon of being famous for being famous. Like Paris Hilton, they're riding on the coattails of their parents' accomplishments/wealth, without having accomplished anything themselves. It has the whiff of monarchism, as silly as that may sound. Again, I don't claim to be an expert on these people, but this is my impression.
I'm not saying all examples of children of famous/rich people are without merit. There are some who even surpass their parents, but that's pretty rare. Vanessa Redgrave is a better actor than her father, for example, so she's not famous only because of her last name, although I imagine it did get her auditions others would not have had access to.
The Kardashian/Paris Hilton phenomena also reminds me of Andy Warhol's line "in the future everyone will be famous for 15 minutes." Obviously this isn't literally the case, but the essence is there -- people driven to be famous, and have their 15 minutes. As if that, alone, is a worthy goal.
I don't get it, though. To me, the idea of being famous is a nightmare.