In O'Conner's "Good Country People" why are the characters' names significant?

Concerning names in "Good Country
People":

• Mrs. Freeman's name is ironic because
  she isn't free--she's a tenant farmer.  Mentally, she is anything but free--she's a
  simpleton who quotes platitudes and is dangerous because she's so simplistic in her
  thinking.


• Mrs. Hopewell's name suggests she sees only
  good in others, as she sometimes suggests.  Yet, she's actually simplistic and
  judgmental, focusing on the difference between "good country people" and trash, which,
  of course, she can't really tell the difference
  between.


• Joy/Hulga changes her name to the ugliest name
  she can find.  The name fits her grotesque appearance and state of mind, but also is a
  rejection of her mother's way of life. 


• Manley Pointer
  uses his manly pointer as bait to seduce and trick Hulga.  His name is phallic, of
  course.  He is the source of evil that ultimately leads to Hulga's awakening.  Hulga
  goes to the barn with him because she, too, assumes he is "good country people,"
  demonstrating that she does share her mother's belief.  When Manley tricks her and
  humiliates her, and points out that is doesn't take a Ph.D to be nihilistic and believe
  in nothing, her feelings of intellectual superiority are savagely
  rebuked.