Nobody wants another breakfast cereal.
Nobody wants a mango-kiwi wine cooler.
Nobody wants 161 different kinds of coffee.
Nobody wants more Howie Mandel.
We have these things because people really want to be told what they want. We have these things because of advertising and promotion.
Libraries need to do a better job of promoting our services instead of pandering to the whims of the people. Businesses that do a better job of promotion will have the people demanding that you buy lots of crap for them.
If our library gave our patrons what they wanted, we would have one huge standing order for pit bull books, and draw the anime way books, and porn fiction, and sex tricks your mom never knew, and gamer programming, and witchcraft spells to replace all the books the people steal, and lots and lots of empty plastic cases where the cds and dvds used to be.
People have never known what they want. never. For proof, do the New York thing where you look up at a building and point. Say, "Oh, my God, look at that." (Actually, that probably worked better, pre-9/11.) And people who otherwise had very important things they should be doing, will stop, and look. Because they really didn't want what they thought they wanted two seconds earlier and this new thing might be better. Your interest in the non-existent thing is advertising, and it works.
If people are told to act like animals, they will. If all you offer at your library is porn on the Internet, then budget for the inevitable stripper pole, because that's coming next.
The historical social benefit from libraries has been that people who want to better themselves have a place where they can go to do it. Why do you want to fuck with history?
Never give the people what they want. Give them what they need, but tell them it's what they wanted. It's like telling your mother you want pancakes for breakfast, but she gives you oatmeal; she knows if you're hungry, you'll eat it.