upon finishing the text, i think my takeaway is that it should be  viewed solely as an attempted historical reconstruction. the politics  presented are meant to document those that existed amongst the migrant  workers, and amongst the people the migrant workers met. if i was  reading the text looking for some deep insight into the political forces  that caused the migrants' struggle, it is because i fundamentally  misunderstood the mandate of the text. if they themselves did not  understand the causes of their struggles, how could the author  demonstrate those causes and still narrate their story fairly, without  mocking them?
in fact, there's some evidence of  mocking. the fruit seems to make them sick, and they seem not to  understand that the probable cause is that it's been sprayed. did that  "medicine" kill grandpa? there's actually a lot of examples of this, but  the narrative seems to be left choppy on purpose, to prevent intruding  into their story.
if steinbeck were to delve into a  deeper understanding of causes, he would have intellectually segregated  himself from his characters, and literally lost the plot.
this  may have been a part of the reason that the reverend was left  underdeveloped. it seems clear that steinbeck wanted to use the reverend  as a sounding board, but he was shut down early in the text. steinbeck  scolds himself by pointing out how quiet the reverend has been, whenever  he's reintroduced. then he takes him out of the story at a point where  he could have been louder, only to reintroduce him in order to  kill him off completely. but, see, there's a point where john says that  he expects to see the reverend again - once again indicating that  steinbeck intended to use this character to speak.
was  the reverend silenced so as to not interfere with the story of the  migrants? and, if so, is there an unedited version with deeper dialogue?
i  would post the essay here, but he wants it done by hand. he says we'll  spend enough time typing when we're older, and that we're still young  enough that we should be practicing handwriting.