Pensaboy, it depends on your point of view. Lyrically speaking they are not simple at all, I'm not talking about Beryl right now indeed.
Music-wise, simplicity is the key to all great songs. I mean jazz standards is good examples of timeless and powerful yet simple songs.
With music often all the difficulty comes only with the structure of it. Take 'Telegraph Road'. It's extremely big, but well structured.
That's why I call it simple