A highly moral book based on Christian values? Why would anyone go into that book with that expectation? Rowling has always used morality lessons within her message, but that wasn't her main goal. Although if you wanted forgiveness and redemption, most of the characters did have that in one degree or another. Even Dudley and Draco had turnarounds.

Harry did grow up. He maturely accepted that he had to die to save the school. He even managed to forgive Snape, which was far more magnanimous than he needed to be. As for Lily and James we, we saw what we needed. We had a nice glimpse off their happy domestic life. The book was never focused on them. Only people who questioned the positive information already given to us about them by other characters in the books or by Rowling, seemed to want more confirmation.

Why would anyone be attracted to Snape? It all seems to be a sublimated sexual attraction that is entirely safe since he isn't real. He was very controlled and constrained, so it would be easy to imagine his repressed passion. He was one of the few adult characters available for romantic imaginings who had any significant page time. Sirius and Lupin are two others with similar followings. I used to be attracted to Mr. Spock on Star Trek. It was the same attraction to a cold unavailable mysterious character like Snape. Except Spock wasn't also a nasty jerk who was cruel to children. I have higher standards for my fantasy lovers.

My point is still that it is folly to blame an author for not writing the book you wanted or not taking a character into the direction you wanted. And if you feel you were misled by previous books, then maybe you misread the indications.