I can take on board what MAB says but to a certain point disagree with some of his POV. IMO there is a time and a place for sad songs and crying in beer. Always has been and always will. That means that people do not always just like happy or uplifting songs it simply means that there is room for both......and a time and a place for both. In order to feel one emotion you must first experience the other.
Songwriting is about empathy....capturing the emotion of the subject matter and taking the listener to that time and place.

I also disagree that we should always write in teams and include young people to keep us up with the times. Spontaneity and originality can be a lone venture...lots of great songwriters work alone. Again there is room and a time and place for writing in a variety of ways.
To ALWAYS write as part of a team can become a bit of a production line where folk are just writing to a formula.
Maybe that is why country music today especially Nashville is seen by some people as stagnated and clonish following the same formula and being afraid to let originality and creativity flow.

http://www.soundclick.com/bands/songInfo.cfm?bandID=687727&songID=5238055