I'm going to come right out and say it: I didn't think Pixar's Inside Out was very good.
The three "human" characters were normal. Nothing interesting going on there. The emotions were caricatures of emotions and definitely not well-developed characters. And the scenes featuring Joy and Sadness navigating long-term memory were so slow that I fell asleep, woke up having no idea how much time had passed, but it didn't seem I had missed anything important that affected the story-line so I was able to keep watching. I feel like you shouldn't be able to tune out of a movie for extended periods and still be able to follow along, but you could with Inside Out because there just wasn't that much going on. It was, I think, a rare example of a story that was too simple.
That last Pixar movie I saw was Brave and I feel like my criticisms of Inside Out could be equally applied to it as well. I saw Brave in theaters and regretted that choice. So much money to spend to hear a story that I feel like I've heard a hundred times before, and got bored with by the time I was in the second grade.
What happened Pixar? You used to be the king of great storytelling! The last Pixar movie I saw and really liked was Up; not a perfect movie, but still pretty good. The last really great Pixar movie, in my opinion, was the first half of Wall-E.
The next Pixar movie, The Good Dinosaur, looks like it's going to have the exact same issues as well. These are just not very good ideas, they're too simple. The characters are one-dimensional, which makes them hard to emotionally invest in. I have some theories as to why Pixar has been trending in this direction and a lot of it has to do with internet PC homogenization. Compare Toy Story to Inside Out and I think you'll see the difference. Toy Story was irreverent, the characters were naughty, they sometimes hated each other a little. But no one is even bad in Inside Out. There's no villain. There aren't even competing interests. The message in fact seems to be that every emotion is valuable. You can't argue with that, but that doesn't mean it makes an interesting story.