If forget where I read it, but Abercrombie acknowledges these issues himself. It was probably in an interview or in the author's notes in one of the books. He's pretty honest about the fact that he's riding a wave of "grimdark" fantasy being popular in the wider culture, and it's not something he invented.

I don't know how much fantasy you read in the 90s and early 2000s. There's a huge swath of what I tend to think of as Lord of the Rings fan-fiction. Not that a lot of those books aren't good, and very entertaining to read, but they are obviously and totally buying into the sort of framing that you got in LotR.

That is, there is good and there is evil, and it's very obvious which is which. A lot of the characters tend to be ancient and powerful, and they are always true to their nature. There are noble kings, and powerful wizards, greedy dwarves, and wise elves, and so on and so forth.

Also, usually there's a hero's journey that is very explicit. The naive farm boy becomes the chosen one who saves the world, etc.

Abercrombie's books, and the First Law especially are basically just a rejection of that kind of fantasy. They're not making a wider point about how the world really is, but they are exploring parts of human nature that those books never could.

Does that make him a master of character? Not really. I think there are a lot of novel writers that do that better. But he is bringing something refreshing to the fantasy genre at least.