I find the question rather irrelevant, which is meant as an actual answer and not a dis on anyone for asking it or posting it. I really enjoy reading books, and admin at
a Science Fiction message board where we discuss them (among other things.) Is "cultural significance" that important compared to whether people who's opinion you appreciate like a book or not? Not for me.
Certainly, novels continue to be a source of inspiration for cinema (that usually doesn't live up to it's source material) and even for video games these days, but then so did the Dukes of Hazard, so I don't think that's particularly a measure of worth. A novel is just one form of media, and it still works for many people. It doesn't usually have the influence on society today of moving image media, but then I suppose something like the Davinci Code does on that sort of mass market level. I am personally not much more interested in reading it than watching Desperate Housewives or American Idol though.