"Hating", no. He wanted to write books like The White Company. He could have done! But Holmes was more popular, so he asked a higher price, got paid, and continued with the Holmes. This is like a dialog with the public. It's not that he had instructions such as now make Holmes a vampire and was compelled to obey. The level of his obedience to the public was modulated by his level of liking money. Less money and more freedom was an option. I can't find the Le Guin foreword, but I wonder in what way she was convinced.

But anyway, no, you are not on rails in your creative "job", and it is self-directed, unless you think you're compelled to make X amount of money and thus have no choice but to write loathed vampire books, without even the option to go and work more happily in a factory.