I disagree. Archiving information for future researchers is valuable, but giving access to information to people right now is also very valuable. Most people's access to texts for research is very shallow, unless they are part of a research university. Google Books hosts many works that are out of copyright, but there is a century-long dead zone that is inaccessible.
I write a history of technology blog and the Internet Archive lending service has saved me thousands of dollars and many hours that it would have taken to track down the same research materials on eBay. Realistically, I just wouldn't have bothered, and the material I write would be of lower quality or not get written at all.
(That said I do agree that the emergency library was a strategic and legal mistake.)