Published in 1960 this classic was never a dark or pessimistic tale imo. It is just a classic and realistic description of 1 mans moral decline that most people submit to without even realising it.
As Steinbeck knew well the American dream was always an empty dream. Dog eat dog, rat eat rat was always the reality and this novel brilliantly describes Ethan's slow slide into dishonesty as the pressures to conform build up around him.
That was 1960 and today's societies, governments and peoples have declined so far into moral decay they would barely even recognise Ethan moral dilemma. Most people today would certainly not understand it because Ethan's moral dilemma is not a dilemma for more than 90% of the population any longer. Lying, deceiving, back stabbing & criminal behaviour to get ahead is just normal business today. Believing in nothing but your own personal advancement is the now norm and you're considered a curious old fashioned dinosaur if you have other motivations. There's very few true believers left on this planet and they are dying off fast.
The self seekers will wonder why Ethan struggles with any moral dilemmas and will find this great novel both tedious and boring. You'll see lots of those in the previous reviews here. And they won't like the ending to this great novel either.
But for us dinosaurs from a bygone era that are still left on planet earth this novel will remain as one of the greatest works of western literature.