Wonder was a soppy feel good story. It had all the expected tropes. The dying dog, the helicopter Mom, the angsty and overlooked teenage sibling, young love, troubled friendships, and a child of exceptional strength. It was well made and well played.
I don't think breaking it up into character-centric sections added anything to the movie. It would have worked just as well using a linear narrative. In someways, the side narratives detracted from the whole. I got that the sister felt forgotten without needing her to have a whole section of the movie. I didn't care that much about the sister's friend falling apart. Neither piece enhanced the central story which likely didn't really have enough to warrant a feature film. All in all, I thought the movie could have been a great after school special.
Maybe breaking it up into a "peak TV" prestige series would have allowed more room for side narratives to have more weight. The sister's struggle with fitting into a new school where she isn't defined by her brother and her friends have seeming cast her aside has plenty of meat for an hour or two of TV. The lost friend's home problems and eventual reunion also has some meat. I'm sure the bully has a back story that could fill an hour of TV.
Wonder is worth renting, but not paying full price. Read the book instead; it is more bang for your buck.