I don't necessarily agree that Anne isn't undeserving of our sympathy in this excellent novel. If we analyse Chapter Ten closely, we can see that actually there are a number of excellent reasons why we should feel sorry for Anne and her situation. Note how she justifies her decision to Michael and the others:
I'm a woman--I've a right to marry and have children. There are three of you and five of us. Are you saying that two of us must never marry? Never have any lives or homes of our own? If not, then two of us have got to marry norms. I'm in love with Alan, and I intend to marry him.
Anne presents a clear and cogent argument based on the facts and also her right to enjoy life as much as she can. Based on this perspective, we can see that Anne certainly has a point. Why should she be forced to live a life without marriage and having children just because there are not enough telepaths around for her to marry? In addition, the way she hangs herself also makes her a sympathetic figure, as she is forced to face the fact that she is different, and that this difference is something that she cannot escape.
However, what definitely does not gain her sympathy is her act of cutting herself off from the other telepaths and betraying them to her husband. In a sense, by cutting off all communication and pretending to be a normal person, she is essentially betraying herself as well. The letter that she writes before killing herself could have easily resulted in the torture and/or death of all of the rest of the telepaths. Anne never had the right to put the rest of the group in danger, and as much as we can understand her frustrations, this is definitely something that makes her an unsympathetic character.