Not everything that is written is deserving of keeping.
As for books being readable for centuries -- the moment we switched to dead tree paper, was the moment we lost history.
Paper degrades, and old books quickly turn unreadable unless they are specially preserved. Anything important and worthwhile will remain known and will be continually written down again, and stored in new formats, so it will never really be lost.
You can't possibly argue that we're now in a worse state than in aniquity -- when the Library of Alexandria was burned by the muslims, it destroyed so much knowledge we don't even know how much, and this was all stored in books and pamphlets.
Even if the entire internet disappears tomorrow, almost all info in it will still exist in some form on physical harddrives, optical storage mediums, etc..