That's why I say Complex is easy, Simple is difficult.

Yesterday, like most of the Beatles' songs, is a song that began with the music, and then the lyrics were fashioned to fit the song. That is invariably how I write also. When you create lyrics this way, they MUST fit into the melody, so it's an exercise in matching syllables and meaning, and somehow creating full lines that make sense. The old story goes that Paul woke up with this gorgeous melody in his head and sat down to the piano and worked on it, singing "Scrambled Eggs" instead of Yesterday, and it was even the working title for awhile. He spent a lot of time playing it for other people asking if they'd heard it before, because he couldn't believe he wasn't just remembering an existing melody from some other song. But the simple lyrics he came up with support the yearning beauty of the melody and resulted in one of the best, most covered songs of all time. But put those lyrics in a book of poetry, and that poem just plain sucks.

My belabored point is that there are certain themes that we all relate to, and we say them in different ways, but the same themes truly resonate with us. Unrequited love, lost love, broken hearts, inability to understand our actions...blah blah. We can't always be breaking into new and unexplored lyrical vistas. That in itself can result in overly "clever" songs.