Like most of you, I just saw and loved Toy Story 3. And as I've mentioned before, I recently read and loved Knuffle Bunny Free.
Vague spoilers ahead.
It's certainly possible to tug at people's heartstrings without impressing them critically, but these trilogies manage both, especially in their endings. Why is it so impressive to show children outgrowing toys? I think it's largely that these stories pose problems without easy answers. As we read and watch them, we don't automatically know what the inevitable endings will be. Will Andy and Trixie lose their beloved toys to unknown or horrible (if you go with TS3's portrayal of toddlers) fates? That wouldn't be right. Will everything go back to the way it was? That wouldn't be quite right either.
These stories are honest with us. Relationships between loving children and beloved toys are precious; there's a reason we've followed these narratives from their beginnings. But those relationships don't last to infinity and beyond. The two trilogies found similar answers, and they're good answers.