People at different stages of development enjoy different things in movies. Some of the best children's movies are able to make things scary or intense for the adults without being too much for little kids.

For example, in My Neighbor Totoro everyone is worried that a small child may have fallen in the lake: she's gone missing, they find a sandal floating in the pond, you see people dredging the pond looking for her, and it's very clear to adults and older kids that the worry is she has drowned. But to a little kid it's much less obvious; the actual dialog only says that they found a sandal. This gives a very intense and emotional scene, but only for people who can handle it.

Similarly, many kids' movies need to get the parents out of the way so the kids can be put in situations of unusual responsibility. Some are pretty blatant about this (ex: Bambi, The Lion King) and just very clearly kill the parent on screen, but Frozen handles it way better. You see, wordlessly, the parents boarding a ship, the ship in a storm, a big wave, no ship, a funeral, and then "Elsa gets to be queen!" Clear to adults, who can put the hints together and know what a funeral looks like, much less clear to kids.

There are lots of movies that manage this kind of differential targeting with humor, since it's relatively easy to add jokes that will go over the kids' heads, but I'd love to see more of this in other areas.

(Another one that comes to mind is the way the opening sequence of Up is very powerful to adults, while little kids just get "she got old and isn't around anymore." I don't think this one is handled quite as well, though, because unlike the scenes in Totoro and Frozen, it doesn't really fit with the rest of the movie.)