"...true bibliography is the bridge to textual, which is to say literary, criticism. Before a critic can attempt a definitive evaluation of the contents of any book he must be in possession of every fact which has any bearing on the history of its text." -from Fredson Bowers's 1949 Principles of Bibliographic Description
Really, Fredson? We need to know everything about a book -- its history, context, physical makeup -- before we can do any legitimate literary analysis of its literary contents? Really? Because I really do not buy that argument.
I would offer that the variety of packagings that encase most any book these days -- think the variety of bindings of any given book you read in college, where you might have a different copy, different cover than the person next to you -- stands in direct opposition to this claim for bibliographic necessity. So what if my cover is different than yours? The words are the same, and it's the words I'm analyzing!
I think that these sorts of statements -- the ones that inflate the importance of the appearance and condition of a physical volume at the near-total expense of consideration of content -- are exactly what bother me about the rare book world. I am always hesitant when library students say they want to be librarians because they "love books"; after all, a love of books alone cannot be sufficient to do well in what is primarily a service profession. That said, however, I do love books. And I love them because of the stories, the ideas, and the information that they contain. I love them because of what their words can do. I really think that someone who loves books for their trappings and trimmings -- who judges books by their covers, or their rarity -- is seriously lacking in their book experience.
And yes, while statements that expound on the book's physical virtues alone make me angry, my ultimate emotion is quite different. Ultimately, I feel sorry for you if you can't/don't/won't look deeper, because I can assure you that you are missing something grand.