It's a truth, universally acknowledged that a first draft will be terrible. Even with world building, character development and solid voices in your head. First drafts are inevitably terrible and mine are no different. If anything mine are worse than average because the book plays like a movie in my head and movies use a very visual language to tell their stories. A lingering look between two characters in a movie can convey some strong emotions, in writing you have to use your words and I'm not going to lie that shit is hard. I'm much more visual, but lets face it, making movies - especially the ones we see in our heads is expensive and also (I imagine), like the Trad Pub world probably very hard to get a foot in the door. Writing your own book, being it's master and independently publishing it for people to read is, well, it's easier, it's cheaper and it's a release. Sending your idea out into the world rather than simply letting it build up in your head.