The suggests that Capitalism in the American society turns the individual into a man who is in hectic pursuit of success according to flimsy standards such as the ones adopted by Willy, However we see that in Will Smith's "The Pursuit of Hapyness", the film presents a real story of a salesman who was able to achieve success though he was poor in the same society dominated by the same standards. These are two contrastive pictures taken from the same society, to what extent that is real?
I don't know that we can say it is capitalism or a capitalist system that leads to Willy Loman's failure and his personal tragedy.
True, he fails to make a success of himself. But there are other characters who are successful and happy. This would seem to suggest that the fault is not in capitalism, but in Willy.
Willy likes to play upon tropes of commercial success because they present a convenient, easily understood value system in which esteem and respectability are highly visible/systematicly defined. Loman plays on these notions of American success only because he cannot achieve them. They are an escape. They are a fantasy.
Maybe we can look at capitalism in this play that way: Capitalism is arbitrary and fantastic, while humanity is struggling to find its own way into acceptance.
This view doesn't mean that capitalism is the culprit though. It just means that the system is separate from the human drama (and only interposes in personal life according to the strength and weakness of humans).
In the long run, I do think capitalism is devastating, especially associated with greed. It chews people up and spits them out. Things are great when they are going well, but then when you lose everything you really do lose everything- not just your money but your family too.