Youre right. Everyone should listen to exactly whatever kind of music they want to. Although, some people may be mad when they realize just how much money there is to make in the entertainment industry via tailored mass marketing and subculturing. If they percieve an artist to be insincere or untalented it may be frustrating to know that popular artists are rolling in the dough while more honest acts are barely scraping by. Think about how many songs in the last 1 to 2 years "reuse" elements from other songs. The point is maybe too much money is thrown at the next big pop stars and their labels, in a sense, enabling and resulting in a more homogenous and exclusive music industry. Thats not necessarily a good thing.
That's the unfortunate reality though, regardless of the medium. McDonalds will always make more money than the local burger shop. Michael Bay flicks will always make more money than a risk-taking indie film. And pop artists will always sell the most records, garner the larger fanbases and gain the most exposure. It's always been like this and probably always will. McDonalds is honestly a perfect comparison to pop music. It's cheap and potentially articficial but does it's job (and is infinitely better when you're drunk); however nobody wants to be that guy that only eats at McDonalds. Music is unfortunately a business like everything else, and artists like Ke$ha, for better or worse, are more marketable. The best thing you could do is concentrate on the artists you love, do everything you can to make sure they keep making music, and let the kids like whatevers on the radio; they'll broaded their horizons eventually *knocks on wood*