It first occurred to me after watching Cyberwoman, especially listening to the complaints from some quarters that Ianto "wasn't punished". But he is punished. It's just that Jack, acting as village headman, allows Ianto to work off his punishment in front of the group instead of making him leave the group.

I have to agree with Jack, I'm not sure Ianto deserved the ultimate penalty of banishment. While his actions did result in the deaths of two people, he did not kill them directly and he was acting in the honest belief that Lisa could be saved. Torchwood hadn't dealt with enough Cybermen for there to be a large body of evidence stating otherwise.