I haven't seen the movie, but from what I can understand, the young woman became paralyzed and was in pain so she didn't want to live. The story line is supposed to be about the Eastwood character taking the responsiblility to carry out the girl's wish to die, regardless of the moral guidance of a priest. In other words, the Eastwood character makes a conscious decision to disregard the religious advice of the priest. And, that's supposed to be a good thing in the movie.
Having seen the film, that is where I disagree. The priest, for one, is not shown as being wrong or as holding Eastwood back. The euthanasia is not presented as being the right thing to do. Yes, Eastwood makes the decision to go through with it, defying the priest, but the priest is not viewed as wrong in the film, and Eastwood's character isn't considered redeemed by the act, nor is he as having made the right choice. It's the decision he made, and the audience can decide whether he was wrong if they wish to. I think he was wrong. I'm morally against euthanasia. But I don't think this film takes any sort of stance in favor of euthanasia, but instead presents it as part of the story.
Anyway, that's my take on the film.
Where did you get the impression that it's supposed to be a good thing in the movie? I have seen it, and I did get that impression at all.