Mass production of books

It seems that I've gotten a lot of ideas in the weeks I didn't post. I got this one from an article about how authors are pressured to produce more books in less time, and if this affects the quality of their writing.
I didn't read the rest of the article, because I have a very strong opinion about it (also, I was in a hurry). And my opinion is a rotund YES.
Even if it's the most talented writer in the world, their writing is going to suffer if they're being rushed to a deadline. And today deadlines are awful. How can you write something magical if you have to produce 2 books a year? You don't have time to do proper research. You can't go over and over again your manuscript, changing a word here, pulishing it. Maybe changing a couple of scenes. You have to rush to finish it and then start with the next one, and the next one. And what about the ideas, and the argument?
Thomas Harris takes 7 years to write a book. Diana Gabaldon takes a lot of time, too. Herman Melville spent years in his Moby Dick. And Margaret Mitchell labored years and years over her manuscript of "Gone with the Wind". Even Anne Frank rewrote and pulished part of her diary when she was thinking about publishing it.
I'm not saying that a writer should spent years over his book before turning it in, but I have the impression that now books are considered almost like skirts, or hats, or something you can manufacture in a factory, instead of a work of art.
Because that's what literature is, a kind of art, and you need your own time to create it.