... novels, poetry and short stories is in the field of art. Those in the arts need to make a living and if they can do it from their art, a market is needed.
The rich used to be the patrons of the arts. They still are in some media, but the masses through corporations are the new patrons.
George R.R. Martin has some kind of agreement with his publisher. Writers of his proven marketability often miss deadlines partly because publishers understand that you can't just command a writer to write like the Pope commanded Michelangelo Buanarroti to paint the ceiling (and the back wall later).
What will be will be. Quality is preferable to quantity. Tolkien considered The Silmarillion to be more important than the Lord of the Rings Trilogy, but many fans found it disappointing. Being upset with Martin is like going to a concert and incessantly screaming a song request to the band on stage.
Who knows? Maybe living in Santa Fe has made him a procrastinator.
"Stultum est timere quod vitare non potes." ~ Publilius Syrus