Mainly because she was dead. Your comment could leave one with a different impression. Nobels aren't given posthumously, and she doubtlessly would've been part of the citation had she still been living in '62. Sadly, she died of cancer, which very likely could have resulted from her repeated exposure to ionizing radiation. She suffered for her craft, and the world benefited, even if she didn't. This isn't to say that she wasn't royally screwed by a lot of people, Watson and Crick especially, as they basically stole her data. But they probably would have stole it from a man, too, given the opportunity. That's just how science works, unfortunately. I think that most people these days who pay attention recognize Franklin as the "true" discoverer of the structure of DNA.She didn't even get to be part of the joint Nobel Prize given in 1962 for the research.
valuable clarifications. thanks, b. (edit: deleted double post)