These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: The Grapes of Wrath
Anvilicious: As stated above (Steinbeck was a socialist).
Everyone Is Jesus in Purgatory: Steinbeck stated that there are five levels to the story. Presumably, one is the tale of the Joads themselves, one is the Depression, one is man's inhumanity to man in general, one is why there are so many biblical references, and one . . . Who knows?
It Gets Better: The turtle motif in chapter 3 is just one example. While the symbolism is all right, the fact that it gets dragged out for a whole chapter is a bit much. It also takes them seemingly forever just to get to California.