There are many different factors at play...
1. Most of today's artists are self-centered, full of themselves, and in some cases (ala Taylor Swift) narcissistic.
2. The big, cinematic, orchestral sound, which seems really odd when you're not in a theater and the song is part of the movie's soundtrack (like "Call Me Maybe").
3. A lot of songs today are simply the same words being repeated over and over and over and over and over and over and over again (who is Katy Perry trying to convince that she's awake, us, or herself?)
4. A lot of songs and artists today simply start sounding the same after a while.
5. Everybody wants to be the new GLEE.
6. The music industry in general is really crooked anyway.