I think this debate comes down to a couple of things.
1. From whose view do you look at this from as there are many.
The religion of Idris sees awakening, as well as the giving/selling/buying/acquiring of breath as immoral. This comes somewhat from their history, that they were exiled from their ancestral home by awakeners. They have blocked out of their religious memories where they came from and who they are descended from. Their religion holds that any way other than theirs is wrong, and that nothing can be gained from the giving/selling/buying/acquiring of breath.
Viveanna seems devout in the religion of Idris; however she has been groomed much like a child in any faith that their way is the only right way. She is forced into a situation that is not of her choosing in being given the breath, and as she progresses, she learns about other religions and who she is as a person. Who is to say her decision to use breath as an awakener is right or wrong other than her. She weighs both sides of the coin so to say, and when it comes down to life or death, she finds out what truly she believes. Yes, she could have learned how to give breath to drabs or those perceived in need, but who is to say that the drab/beggar/perceived begger won't turn right around and sell it. Much like the beggar on the corner. If you give him money, he mayuse it to feed himself and/or his family. He may go buy beer or cigarettes or drugs. You never really know. If you in turn offer him food, you have a better indication of what his intentions are.
Siri who has felt like an outcast in her society when confronted with a similar situation to her sister, chooses to embrace her new life. Again she knows the teachings of her religion, and finds that perhaps there is truth in more than just one religion. She finds that she really never knew the other side of the story. She may judge quickly and in some cases incorrectly, but when she takes the time, she makes her own decisions, and if she chooses the wrong decision, she learns from it. She is compassionate, sometimes to a fault in being blind to the truth, but again she will admit she was wrong as well.
With those like Jewel who gave their breath for their gods, in her mind she sacrificed something that she didn't consider important to help her family. Her family was blessed, she feels as a result of her decision. It's similar to one of my mom's friends, who as a child was beaten regularity by her father. She went to a christian church, gave offerings, and prayed that God would stop the beatings. When she was a teenager, she said that she felt a man put his hands on her shoulder one night and tell her that the beatings would stop as she prayed. As she looked down she saw feet with nail holes through them. The next day her father left and never came back. No matter what might happen later in life, she will always believe her religion caused the miracle. Nothing anyone can say can change her mind, and if I had that experience I would be able to say nothing and no one could change mine.
2. The situation in which the breath is acquired.
Those who actively seek people willing to sell breath, create an underground market to sell breath illegally. Brandon wasn't specific in what regulations and safety nets were in place for those who sold their breath, but he mentioned that those who gave their breath to the gods were reimbursed fairly for their breath. The experience Jewel tells Viveanna supports this. Now, if a thug lord is prostituting the breaths of the people who look to him for protection, and they are not benefiting from the selling of their breath, then yes, I feel the issue is immoral, as one gains from something that he perceives is his but actually belongs to another, and the person it is taken from does not benefit from the loss.
Pretty much what I take from this, is that it depends on the perspective you are looking at the situation from, and the complete situation as to how the breath was acquired. There is always more than what you see at first, and the more you know, the better you are able to decide for yourself weather or not you think the choice is right or wrong, and even then, you need to be aware that the choice is not always yours to make. Choice is what makes us human. We may or may not agree with the choices of others, but it is their right to make their own choices, and we can't judge a person because we don't agree with their choice.