I am not quite sure what your point is. Of course a "real" person would have more factors at stake, but we only have 1.5 hours to get to know Riley.
Pretend you are Riley for a sec. You had led a cushie, happy life untill the move and had not had to adjust to any major changes in your life yet. Then suddenly, the new house is a let down, and all of your possessions have been moved to the wrong state. You have no good clothes for your first day, let alone a bed etc. Ok you can handle this hiccup in the road.
Then on your first day, still feeling a bit out of whack, you get put on the spot in front of strangers and have to talk about yourself. Next minute, you start crying and can't control it. How on earth are you going to approach people in a relaxed, happy, Riley way now? Who are you going to sit with at lunch?
You get home and have a fight with your parents. Your dad is angry at you for being "sassy", when clearly you are upset. Rather than being gently asked, you get scolded and sent to bed. You feel like they don't understand you right now.
Later as you Skype your best mate, things get weird. She only asks a few questions before rambling on about the new girl, shows a photo, speaks about how well they play hockey together like they can almost read each other's minds. That is a low blow for Riley who is already feeling isolated in this new city, and now it feels like you are ALREADY being replaced and your previous home life is moving on without you.
I could go on but I'll stop here, I am just trying to show that a little empathy goes a long way, even with film characters. Nobody is "straightforward" at 11, that is a very tricky, transitional age and we forget that as we grow up. I think this movie served well to remind us how much kids FEEL, particularly in times of upheaval. And how important it is to feel ALL of it, even (especially) sadness in order to get through it.