Meh, the real problem was that somewhere along the way she forgot to continue to develop Ron and he became comic relief. You could see the path she was headed in with him, but quite frankly, she never rounded him out. Instead of more of the boy that played the most brilliant game of Wizards Chess Hogwart’s had ever seen, we got too much of the kid who was barfing up slugs because of his wand backfiring over and over. Instead of the boy that played an astounding game of quidditch when his confidence was up and learning from that, they focused too hard in the movies of how ridiculous he was before that, then had him acting like a complete fool with Lavender. It was much worse in the movies than it was in the books.
Ron was supposed to kind of encapsulate a little of the best of the Weasley boys. Not quote as athletic as Charlie, but a little better more than the others, not quite as cool as Bill, but maybe a little more adept than Percy and the twins. He carried some of Percy’s nature for leadership (Prefect) while also being willing to break the rules like Fred & George. He always felt lost in the middle of all of them, but ultimately should have been the best of them.
He was a good enough Wizard to get all of his OWL’s necessary to pursue a career as an Auror, yet they always made him out to be a joke as a Wizard.
I blame the movies. Ron was developing in the books, but by the time you got to the last 2 books, the movies were catching up and I think the movie characterization of Ron as a screwup and as comic relief influenced Rowling. Plus, it was helped that the actor became rather goofy looking as an adult...
