For me, it’s important that the theme supports the gameplay, but never at the expense of a clear mechanism. That means that I will never include a detailed rule just to be closer to the theme.
So I prefer to be involved in the development process as early as possible. Publishers as well as authors don’t necessarily realize that we can contribute a lot through images, that it’s possible to work in depth on the link between mechanics and images. We can thus avoid having illustrations that only “paraphrase” the mechanics.