That's because it's cheaper to automate than pay a software engineer. The economics has to make sense. Writing is tricky. Prose quality isn't there yet for many genres. You can tell AI written prose apart. Maybe it won't matter. Maybe there is demand for it even. Or Maybe we will create genre specific finetunes if there is enough demand for it.

There's a lot of writing that is meant to be read by humans.

Code's ultimate goal, on the other hand, is to be run by computers.