I believe it has more to do with the education system in this country more than anything else. I talk to people all the time who have college degrees and can't speak well or put a sentence together. I won't even get into spelling as most people under 40 can't spell worth squat.
My kids, who are in their 20s, were not required by the school system to learn how to spell properly but were encouraged to "be creative". They weren't taught the multiplication table in school and therefore have trouble doing math in their heads. They were never required to know geography so when we moved from SoCal to NC they had to me show them on the big map in my office to see where it was (they were 10 & 8 at the time). They probably can't name more than a dozen countries outside the US. The worst thing is that they were considered exceptionally smart by their peers!
Education in this country has been dumbed down to such a degree that most people would fail a 5th grade final from 1960. My parents were required to know so much more than we were and, us so much more than our kids. Of course they didn't know how to text message each other so I guess that balances things out.
The letters my parents wrote to each other during the Korean War, when my dad was overseas, are amazing in their vocabulary, structure, and content and these were from people who never went to college.
The ability to communicate clearly and with some measure of skill is becoming a lost art.