I'm not sure as to the controversy caused in Browning's time, but people love sensationalism and horrific elements. I remember reading somewhere that the horror genre's popularity fluctuates with the economic state--it seems that in times of economic depression, people want to read about the fantastic and grotesque. (This has nothing to do with your comment, Chris, I just thought of it.) Anyway, I remember Dr. Shurbutt saying that Robert Browning wasn't considered a major poet in his time; perhaps, unlike the illustrious Enema, oops, I mean Eminem, Browning didn't have the marketing geniuses to popularize him in order to create controversy in the first place. But it's an apt comparison--both Browning's poem and Eminem's song have a slightly batty man narrating.