Even though emotion is essential to a great song, it is not enough. Just because we feel passionately about a song we’re creating, that, in and of itself, doesn’t make it any good.
(It’s like someone who intensely wants to throw the football but doesn’t know the right techniques to do so. The ball goes all over the field.)
We need to be able to facilitate our feelings through the right musical forms and techniques: chords, vocal line, lyrics, hooks, rhythm, production, etc. And, of course, we need to work hard and be consistent. Paul McCartney once said something to the effect that one may write a hundred songs before they come up with anything good!
We should let wise dispassionate ears offer critique as well and ultimately, we hopefully end up with a piece that is a perfect expression of emotion through the right forms and techniques that work.