In 1545, Conrad Gessner set about to create a bibliography of everything ever published, the Bibliotheca Universalis. He nearly succeeded. In 2004, Google set about to create a digital universal library by digitizing millions of books from library shelves. Shortly thereafter the Internet Archive began a project, the Open Library, to create "One web page for every book ever written." Meanwhile, OCLC's WorldCat has grown to over 300 million records from 72,000 libraries. All of these exemplify the concept of some universal bibliography or database that make up what I am calling, for now, the bibliographic universe.
The other side of this coin is the catalog of an individual library (or library consortium). This bibliographic data set is expressly designed to be local, not universal. It does not include materials not available to the library user, and what it does include has been selected with that library's constituency in mind.
The FRBR study is a conceptual view of this "bibliographic universe"; that is, an abstract view of intellectual resources and their relations to each other. To say that Magic Mountain is a translation of Der Zauberberg is to make a statement that is unrelated to any actual example of that text, much less the holdings within any individual library. We can conclude that FRBR addresses bibliographic data universally because it claims to be agnostic to any particular usage of the bibliographic concept, and to be able to define any and all bibliographic resources and their relationships.
The problem that arises, as I see it, is where this universal view meets the individual library. Do you express these relationships between items in your library, or do you express the relationships in the bibliographic universe? If your library has Magic Mountain in English and Spanish, but not in German, should you organize your presentation of data around the original German version, even if your users will not be able to read or understand the title in that language? What if you only have the English version - should this be displayed as a manifestation of a translation of the original German text? Is there a purpose to creating bibliographic information about relationships between works, even if the library does not hold those works?
A key question that we need to ask is: what is the purpose of providing these bibliographic relationships? The answer that I believe I would get from catalogers today is that the purpose of this information is to provide an organized view of the library to the user. While in a large library, works and expressions may be organizing principles, in a small library with often only one version of the resource, the addition of information about the work and the expression could be more disorganization than organization, because it doesn't give the user a more organized view of the library's holdings but adds information that may be confusing. This doesn't mean that the information about works and expressions isn't useful - the work and expression could be used to provide interesting information to the user, but in this case they do not provide a useful organizing function in the catalog.
As far as I can tell, neither FRBR nor the cataloging rules (past and present) clearly differentiate between organizing a library, organizing a larger context within which the library operates, or describing the bibliographic universe. I'll accept that organizing the bibliographic universe is probably out of scope in today's world, but where does one draw the line between the individual library and the larger useful bibliographic context that might be useful to your library users?
This is not a new problem. AACR2 introduced the idea of the work by adding the uniform title to the catalog record. The uniform title turned out to be less uniformly used than perhaps was intended because it was not applied by catalogers to all records where it was applicable. In a library with only one (or a small number) of editions of a work, the uniform title was deemed to be either unnecessary or not worth the time of the cataloger. This worked fine in individual libraries but caused problems for sharing and in union catalogs. It also makes it more difficult to move from today's cataloging records to a FRBR-ized catalog, since the essential clues about works are not provided consistently.
FRBR is a conceptual model, but it isn't clear to me what context it is modeling: a library catalog, the conceptual collective of all or most library catalogs, or the bibliographic universe. The original task was to model the essential things of a library bibliographic record to respond to a set of user tasks. However, at the 30,000 foot level at which FRBR operated, the questions about how one would serve users in a particular library is left open. The FRBR user tasks are a look at the existing concept of a library catalog and what one mythical "user" does when approaching it. It also is a look from the point of view of a large library catalog: no one on the study group was from a small or even medium-sized library. FRBR is very much a top-down look at the bibliographic world. If we look at the library bibliographic world from the bottom up -- either looking from the point of view of individual users, or of individual libraries, then we would need to see the FRBR concepts as possibilities, not requirements; possibilities to be used as appropriate for ones particular situation.
We know that a given library serves its particular users, not the "universe of users." The best service for a library's users is to allow the library to make choices that are appropriate for those users. For that reason, requiring libraries to present, in their catalogs, data that has the bibliographic universe as its context is going to be detrimental to library service. At the same time, it would be ideal to have a true catalog of the bibliographic universe available from which a library could draw information or could create links as a way to expand its catalog information for users who need more. For example, the user who looks up the Chicago Manual of Style should be able to learn if the copy the library holds is the latest version. The user looking for "Harry Potter" and seeing that the library has copies in English and Spanish should be able to ask if the book was translated into Vietnamese (yes) or Tegulu (no).
It would be naive to say that we have no use for a bibliotheca universalis. However, a bibliotheca universalis is not a library catalog. It would also be naive to say that every library has the same needs regarding bibliographic data. What we seem to be lacking is the way to bridge the gap between the 30,000 foot FRBR bibliographic view and the needs of the individual library. I think we have the technology to do this today, and some of the possible answers can be found in general databases like WorldCat or DBPedia. It's the connection between these that needs to be designed.