What a stupid argument re. GRRM.
Writing is subjective. No one would argue Martin's anything but sloppy. But within the Fantasy genre he's a great and his early ASOIAF are widely considered among the greatest fantasy works of all time.
He's not even really comparable to Tolkien stylistically. Tolkien is the better writer, Martin the better world builder. The characters and world he has created in ASOIAF are timeless - Relateable, flawed, complex. He's incredibly adept at bringing across their emotions and internal conflict to the reader and keeps the series grounded in reality despite the fantasy elements - The historical parallels and real life themes hit home hard.
Whatever pretentious stance you want to take on reading you can only measure a fictional book's quality by the impact they have on the reader - And there's not a lot of books that tie you up emotionally like ASOIAF does. It hasn't become a global phenomenon for nothing - If any fictional world could be so endearing then you'd see a lot more of them.