They could’ve easily made him the stereotypical “chubby friend” who just loves food, says dumb things for comedic effect, and is one who gets picked on by the rest of his friends. This trope is so common in films about groups of young friends, guys or girls, mostly young and high school aged. But they didn’t do that.
This kid is smart. He has an imagination. He’s open to all possibilities. He’s observant - he’s the one who noticed the compasses.
Yeah he brought food for their excursion, but not because he’s obsessed with it or he brought it all for himself. He was being logical. If they were gone for a while or doing anything strenuous, yeah they’d need energy. Candy, chips, fruit, and trail mix.
The only thing he gets made fun of for is his lack of front teeth, and it’s only by the two bullies at school. His friends aren’t “pity friends”.
tl;dr Dustin is the most beautiful little cinnamon roll