As a researcher, one thing I hate when going to a library is closed stacks. You know, fill out the order slip and wait for the book(s) to be delivered. If you have exhausted your research check-list and need to look for other options or just want to browse to see if you missed any goodies - you can't.
While researching my Cawby family in SLC, I was following a lead on the Catawba River in NC offered by a fellow researcher. Going through the NC section of the library, I came across a book on the settlers of the Catawba Valley. That book opened the door to deeds and family members that helped flesh out the Cawby story.
With closed stacks I might never have found the book and another 80 spelling variations to go with the 60 or so that I already had!