Why not more popular?

I loved this film. I'm puzzled that it hasn't been comparable to the popularity of The Wizard of Oz (1939). It's a similar film in a lot of ways.

One thing I particularly appreciate is the way the film makes light of the nuclear scare. I remember as a kid in the late 50's, a few years later, that people were scared to death of atomic war, and for the makers of this film to make jokes about it must have been comic relief. In the film, an atomic bomb is just part of the little boy's fantasy world. I imagine it was for some kids.

"Extremism in the pursuit of moderation is no vice."