This is because I think it's the only fictional library that the character visited to find pleasure reading. Everything else is functional. One researches one's history, one's sciences, one's magic, but fiction in particular only features if it's the true legend they will be using to find the MacGuffin.
In one respect, that's a tribute to the writing skills of those authors who perpetrate libraries. Robin McKinley was among the few to insert a library for pleasure reading because very few stories are moved forward by the use of a library for pleasure reading. I vaguely recollect a few others where the library was a meeting location, and pleasure reading could be used to motivate the unintended meeting, but to Beauty, going to the library for the books to read was a significant act. (Plus, of course, her meetings with the Beast.)
To be sure, there are the Great Big Libraries of Everything, which might be nice, as long as they had an adequate card catalog, but no one seems to raid them for pleasure reading.
To be sure, I've got two stories in progress in which libraries are crucial. In neither one does a character raid them for pleasure reading. I'm not even sure they could be thus raided, since they are research libraries.