The music board at the cmt.com forums has a discussion currently going about the singer-songwriter era in country music.
As the subject is brought up, it makes me realize that's the main problem with today's mainstream country music. There are basically no female singer-songwriters in the mainstream country genre today. Very few of the females even know how to play an instrument, let alone know how to write a song. There still are a few male singer-songwriters in the mainstream country world, but it's becoming much rarer than in previous decades. Most of today's singer-songwriters are in other genres - most notably Alt-Country, Roots, Folk, Rock or Indie.
If you think back into the history of country music, there have been few female singer-songwriters who made it to the forefront, namely Dolly Parton and Loretta Lynn. While on the other side of the gender scale, there have been a lot of male singer-songwriters throughout the history of country music. However, that number has decreased significantly in the past two decades.
I'm guessing the singer-songwriter decline in country music is the reason why the mainstream country sounds no different than anything that's played on the pop stations. The songs are all written by the same people.