There is a certain accessability to "simple" song structures, yeah. That's not to say that all popular songs need to be "simple." Its also no mean feat to write a "simple" song that isn't boring. It takes a fair amount of musicianship (expressiveness, nuance, etc.) to get a 3 chord song to work well. That applies doubly to the lyrics- simple music and simple lyrics can be a recipe for yawns if they aren't done VERY well.
It also takes a high degree of musicianship to make a more coplex arrangement work, but its been done many times. Granted, the simpler structures
tend to dominate the popular categories, that doesn't mean that simple is the ticket to having a popular song.
In the case of my songs, the most liked tunes that I have (in terms of a general audience- not my friends) are definately the less complex ones. I don't write many complex tunes, though, so I'm not really a fair sampling.
Yup, Vox- this is a good thread.
Oh- I have to agree that bridges are VERY important in simple structures. You only have one chance to throw in a different perspective and add some emphasis- it had better be good!
Take care,
Chris