Smart was kidnapped at gunpoint in a $2M home while the family was sleeping. The family publicized the incident to the maximum in order to enlist public support, including supplying pictures and videotapes to the media, hiring a PR firm, and giving press conferences. Tantalizing details of the crime were released. The story has stayed in the news because puzzling information about suspects keeps getting announced. And yes, the girl is cute.
The Patterson story is also strange and tragic, but it just doesn't have enough of a story to maintain public interest. 90% of what makes the Smart story interesting to the public is missing in the Patterson story.