Steven C. Barr's views are congruent with my own.
Google is a good model to consider. How useful would Google be for most of us most of the time if it only indexed important sites and the most important parts of those sites on the internet? For me it would have very limited usefulness. Because Google indexes everything and doesn't try to make a decision as to what matters we can find things that are amazing.
The expense is for conversion to Google-friendly records from paper/film/tape and Google does not YET index sound or image records for content. That raises the ante somewhat (understatement).