We agree that sometimes unfinished great work is better than finished, subpar work. Of course, neither Wheel of Time nor A Song of Ice and Fire is "great". When I think of great unfinished works, I think of Dead Souls or The Brothers Karamazov, which were supposed to be the first parts of a trilogy and a duology, respectively.

The first 6 books of Wheel of Time were good by the standards usually applied to pop fiction. After that he dragged out the series for monetary reasons.

Having said that, Georgerr Martin has made any monetary considerations Jordan had seem positively insignificant. He wrote 3 good books (to Jordan's 6) and then wrote two terrible books. He also seems incapable of finishing the series now and, given both his girth and age, multiplied by his writing speed, he will also die before finishing.