Sorry, I don't think popularity should be a factor in library decision-making. Extremely popular books driven by massive marketing campaigns predictably translate into the same book being available for only a few dollars months later. This all sounds like it's driven much more by the needs of publishers than library users; consider that the more reduced the selection, the fewer people will come to use the library because they can't find enough interesting material to read.

My local Half-Price Books (a second-hand bookstore chain) has a vastly better selection than my local library.

This is a great way to lose what's left of public support for libraries. Going (more?) elitist is really not the way to go here. Your average person should be able to find utility in a library.

University libraries of course might be a good exception to this rule. But your local public library should be a way to make reading accessible to the average middle to lower class family. And that means providing the materials they want to read - not what you think they should.

It's always going to be a balance for librarians. They don't get to operate in ivory towers disconnected from those local taxpayers whom fund them.