Silly question, right? Readers don't question a poet's motive for writing poetry.
Unless the poetry is a 300-page book.
I have written two novels in verse. Both have gotten some attention from agents, and one of them from editors. The response from one of those editors regarding my book was something like this: "I don't see a reason for this to be written in verse."
And in researching agents, I will occasionally come across one whose policy concerning verse novels is something like this: I will consider verse novels as long as there is a good reason for the book to be written in verse. What does that mean? What constitutes a "good reason"?
I don't mean to be snarky. I understand that verse should not be a gimmick. You shouldn't try to write a verse novel just because you see a trend.
I take that a step further. I don't write anything just because I see a trend. I write the stories that come to me, in the way they come to me.
When SHARRA'S WAR came to me, it came to me in verse. To me, this book was meant to be told in verse. If I tried to rewrite it as prose, it would lose its power.
The same is true of HOUSE OF BONES. Though the story didn't turn out to be as dark as the original opening poem suggested, I still stand by the verse format. It works.
Both SHARRA'S WAR and HOUSE OF BONES flowed from my fingertips as if they had already been written and just needed to be put down on paper. Yes, they have changed a bit since their beginnings. But their stories, their voices, are the same.
Why do I write in verse?
Because my stories tell me to.