I write because, if I didn't, my stories wouldn't exist. It's my job to bring that story out, and be honest about it. If a story requires more skill, I need to acquire more skill, but if the story is actually trash... then that's what it is.
There is no wrong reason to write. And if you worry about being good enough -- stop, you aren't good enough, you never will be good enough, because you can always be better. Just keep working, and keep learning to bring that story closer to what it is supposed to be, not what some one else tells you it's supposed to be. How would they know? They can't see the story in your head.