We've slacked dreadfully on matters interesting, often because I look at what's going on in the world anymore and think, do I really want to bitch about this? Generally, not. Have arrived at saturation point, and find it much smarter to focus on matters close to home that I can actually influence for the better. And yet, every now and again, things come up. Observe.
THE 21st Century Library? I am wondering, possibly "one kind of" 21st century library. The goals here are praiseworthy, and I will not argue with them. However, they provide a very specific principle. If you actually want to FIND anything, another tactic is needed. And while your heroine's a big fan of unanticipated discovery, she also knows that closed stacks materials often end up there since if not they'd be stolen. Particularly all that stuff up in tier 17 of 7th stack. Just saying.
Bottom line? We need both. And we privilege one library example over the other at our professional peril. JMHO, YMMV.
As the library rapidly emerges into something that looks quite strange than it did just a few decades ago, it is significant that librarians not only become conscious of this evolution, but that they vigorously get involved to help redesign the foundation in ways that are reliable with the core mission of libraries. Changes to libraries are unavoidable, and if librarians do not get actively concerned in determining those changes, it is likely that the 21st century library will bear very few of the core missions and ideals that have historically been connected with libraries.