Nailed it! Decoration, digression, didacticism in equal measure. The results are instruction and delight both, just as Horace would have had it. The lesson—Depression specific, and much more general than that—is made effective because we see life going on around the lesson. For instance there’s a nice detailing of each agricultural stage or task. (Again, similar to Santa’s workshop or the clock store or the china shop.) Furthermore the ploughing and planting and all are each graced by a nice little gag. These jokes are funny, but they’re also performing a deeper function.
We see that the chicken family has to work hard. These jokes relate to imaginative chicken-specific ways of surmounting various agricultural challenges. (These are little creatures, after all—sort of like the kids watching the cartoon.) The gags also mean/show that the chicken family is having fun while it works. As a result we enjoy ourselves too. How wholesome!
The time-lapse growth of the corn is really nice. It’s enhanced, yes, but unlike the usual cave-of-wonders fantasy, this boon is actually attainable, even ubiquitous. We’re not likely to ever win a lottery, or receive huge out-of-nowhere inheritances, or say “Open, Sesame” and actually get any results. But agriculture, or your own garden? (Having and raising your own kids?) There are too miracles!
On the other side of the equation, and unlike the also excellent grasshopper-and-the-ants scenario, the profoundly un-helpful, un-industrious Peter Pig and Donald Duck don’t get any second chances. They wouldn’t help, so they won’t eat. This isn’t sanctimoniousness, mind you. It’s justice. (Notice that they’re a couple of frat boys.)
Finally, The Wise Little Hen features terrific mid-thirties vocal harmonies, and the hen’s solo singing is hilarious, to the point of joyful.