I would not confuse being able to give an emotive performance and establishing a good connection with the audience with good songwriting. That is good performance no matter who wrote the song. I mean if Marianne Faithful or Mick sing "As Tears Go By", its still a heavy duty song as long as its done well - doesent matter who wrote it.

Maybe the elements of songwriting and the skill requirements vary with genre and form - a ballad for example needs to tell a story, put the person in a location - a love song is going to need similie and metaphor. A song about a feeling of sadness, joy or an event, needs some specifics that are generalizable to a wider set of circumstances (audience).

Just some thoughts - I have read some sites about song requirements and rigid structure and formulas, It makes sense but I do not take it too literally - one of mine, broken rainbows,(www.geocities.com/retrancer) has no chorus at all, no bridge, and no break. still it is one of my more popular tunes. The rhymes are precise generally, and the wording and metaphor simple and direct.