It is not difficult or beyond reason to deduce that the Smart family is a troubled family. And, the abduction was not a simple kidnapping of an innocent little girl who was sleeping in her bed at night. Even according to earlier police records and prior interviews with her family, little Elizabeth began running away from home for extended periods of time before her 10th birthday.
Every picture that was shown to the public during the time of the kidnapping depicted Elizabeth as a much younger girl. Part of the reason for public animosity is the deception. Sadly, there are many, many children kidnapped each year with worse end results. So much publicity, funding and public support were garnished from the PR spin that was placed on this story, people feel that the public was deceived.
The image portrayed by the family, (specifically the father), the press as well as the media firm that was hired by the family to garner funding and public support were tools that were representing a certain image of a child that was deceptive.
Certainly one might argue that the only issue that mattered was the abduction of a child. I lean towards this view. However, I can certainly understand how others might be just a little pissed off at the way the Smart family manipulated the media through the entire event.