A writer with that mindset will never attain or keep readers. If a writer doesn't care if readers enjoy his books, then he will not gain readers, and hence will wind up unpublished.
Sorry but I'm gonna have to disagree with you on this one. Sort of. The writer should care about whether people enjoy their writing or not, but what Mori said is true, there is no obligation for a reader to enjoy a book. This is why I'm so hesitant when I buy books. Just because it looks like it'll be good, or sounds like it'll be good, doesn't mean it'll actually be a good book.
I like vampires, but I sure as heck hated Twilight.
So while a writer should care whether readers like his book, you can't get too wrapped up in that, because not everyone will. And readers should know that you won't necessarily like the book you buy, that is a risk you take when you purchase it.
As for GRRM...I got less than half-way through that first book in this series before I put it down for other things that I might actually enjoy reading. I'm not angry at him for writing a book I didn't enjoy, because lots of other people love this stuff. But I wasn't obligated to enjoy it, and I'm actually in his target audience. But even if I had enjoyed it, I'd still be waiting patiently for him to finish it, not only because I'm a writer and I understand that shit happens and you need more time to make the story work, but because even as a reader I don't feel I'm entitled to a story. He never had to write that story down, he never had to publish it. It wouldn't have killed him if he had kept it to himself. Plenty of people do that, it's why the world isn't filled with writers. As a reader, I am glad that there are people out there willing to share these stories with me. And there are plenty out there, so it's not like I can't just read something else while I'm waiting for a series to finish.