In terms of studying historical books, it is blatantly obvious that nothing beats a hands-on experience, where one is viewing the actual books and physically touching them. Seeing such works up close is the only way to truly appreciate all of their intricate details and get a sense of every aspect about them. however, this is not to say that there is no value in viewing pictures of such materials. On the contrary, pictures of historical books allow for a convenient viewing of them which, in some cases, is the only way to see them. Simply put, not everybody has immediate access to such materials, since they are often kept in museums or private collections. So, pictures allow for people who other wise wouldn’t be able to see such materials to study them.
I agree, unfortunately there are just not enough rare or historical books to go around. Which you would assume since they are rare for a reason. However, just seeing a picture of a rare book does not compare to an actual viewing. The old books have presence about them, they have character. Nothing can really compare with holding one in your hand, realizing how many people this book has been in contact with; the history of the books itself is almost more important than its content.