I think that the library should provide carrying bags for checkout with books. Sometimes you check out books that are too big for your backpack or you have too many of them so they don't fit, and you have to carry them awkwardly out in your arms. This is heavy and impractical, especially in the rain.
If there were totes designed to allow for easy carrying of large, heavy bookloads and protection from the rain it would be far easier on those doing big reasearch projects.