Respectfully disagree. Martin's "reality" is what we would be like if there were no Sovereign God running the show. God calls real people to be better than that. I think Martin has done a good job depicting a Godless world - but that's not realism (except in leftist fantasies).
Martins take on reality, in terms of human behavior anyway, is what really did happen during comparable periods of history. People only sometimes behave as we would like them to, and powerful people less than most.
And this is normal in literature, the greats not excepted.
If you make such an objection to Martin, you must be similarly appalled at Shakespeare. Titus Andronicus (ok, lets handicap by page count) has Martin beat by a mile. Throw in the rest of Shakespeare’s stuff to pad out the pages and the sheer volume of violence, immorality and villainy trumps Martin handily.