I'm curious, were they ever that stereotypical "shh" environment that movies claimed they were? Because no public library in my lifetime was ever like that (just smaller school libraries), but I can't go back very far. Most libraries I've been to have multiple areas or floors, some which are quiet and others which are allowed to be noisy.
They were "shh" back in the day, but with time they have become more of a place for activity for the community. When I was a kid in the 80s and early 90s they were definitely more strict with keeping quiet, especially in the reading halls. Library history is actually quite interesting, and the whole development of the library as a key element in building and supporting democracy and community, is worth looking into.