For some of the same reasons you might buy something from a local store instead of buying online - you can see actual faces in your community on the way, your library gets usage metrics that help it keep funding and stay around, you might be there already for something else, less time digging around in a screen ui and more time moving in 3d. I also like that the rip itself is totally offlime and not traceable. And it is just stressful wondering if something pirated has something nasty snuck in, however unlikely it is much less likely from a library dvd. Don't if you don't want to, but there are perfectly good reasons.

Exactly this. I could easily just torrent as much as anyone, but I don't necessarily want to meet the low bar. Also, my career path is one such that if I were to ever receive a letter from an ISP suggesting my sailing of the high seas was a bit much, I'd be fired and blacklisted while being forced into a new career path.