I agree with all your points. Before this reading I had not decided on a particular focus, but John has become more visible to me during this read. I did neither seek nor want it, but his total lack of appreciating the right values is so obvious. My abhorrence for his wife has long been established, but this time around my eyebrows has been raised in astonishment over John several times.
Can a man be understood and respected who
1) - actually loves(!) and admires Fanny (and Mrs Ferrars)
2) - breaks a promise to his dying father (the infamous one)
3) - judges absolutely everybody's value based on their bank account, estate, carriage and manner of dress
4) - always fails to understand what the right thing to think and say would be (as Maisy's quotes easily shows) ?
I tried to find clues as to what his defect really derived from, and my conclusion was that he must be born that way. He shows no ability to imagine other people's viewpoint (a trait he shares with his wife). His father must be aware of this as he finds it necessary to urge him to support his step-mother and sisters.
He and Marianne are on the opposite sides of the scale. Marianne learns a lot from what happens to herself and the people around her. John (and Fanny)are as self-centered when the story ends as they were when it began.