Almost everything you said is wrong.
What was Dany if not a gray character?
Bran is not an Emperor. He's just a king, and him being king has no bearing on Sansa's position because the North is now a completely separate kingdom. Bran is pretty annoying though so I'll give you that, but his powers would potentially make him a good king.
Tyrion is doing what he's been doing, but now he actually cares as opposed to before when he was just doing it to fulfill his father's desires.
The nobles set up a council and ended lineal succession. Those are pretty substantial changes. I'm not sure what you mean by they didn't learn anything.
By the end of the show, Dany and Jon were the de facto main characters. One was forced to kill the other and then essentially banished because of it. How is that not bitter sweet?
It's cool if you didn't like the ending, but everything was reasonable.