Same. But then, my favorite part of Moby Dick is the boots-on-the-ground overview of whaling, a whole industry I'd have no concept of otherwise.

Why?

Because I enjoy historical factoids, geography, history,... same reason people watch history channel.

Also, when authors go on these tangents, it can inspire a passion, and it will move worlds. The hunchback of the notre dame saved the church from demolition and became a totem, and it was precisely because of Hugo waxing lyrically for hundreds of pages on end about the atmosphere and architecture of medieval paris. If he had stuck to just the plot, the novel would've been, maybe more readable sure, but nonetheless poorer for it.

And lastly, because if you're in a class on western literature these long winded 19th century reads are a rite of passage. you have to do your part to carry forward a shared reference, one that transcends time and space. school is as good a time as any to make that effort, unwillingly even.