While I love your optimism, the fact of the matter is that George RR Martin, like most of the readers and viewers of this universe, is much, much more interested in the "spunky anti-establishment tomboy" than the girl who adhere to fairytale tropes. In this fan's eye Martin already messed up: Sansa stopped being a main character in his books after A Storm of Swords, and the so-called "Vale-arc"? Non-existent save for a proto-chapter from the maybe, perhaps, if he can be bothered upcoming book Winds of Winter. Sansa hasn't been seen since A Feast for Crows (3 pitiful chapters in all of that), published in 2005, so most talk about her development is pure speculation. Also, potential spoiler for WoW:
which if that's true, makes her dumber than a box of hair, and also not what I've been waiting 13 years for. And I say that as a massive (disapppointed) book-Sansa fan.
As for "incompetent writing and inconsistent characters" I present to you: A Feast for Crows and A Dance with Dragons.