I think it stems from a deep desire to keep sexual RP away from my gaming table, and when I read SR novels I connect with them on a Gamer level. Every character in the book is a character someone at my table is playing... rather than other Fantasy novels where Characters are just characters to me.
Years ago, in a SR group working through some Virtual Seattle games, I GMed one particular game with my wife sitting on my right. She played her PC seducing the PC of a guy sitting to the left of me. The repartee passed back and forth in front of me, leading to a 'successful' conclusion.
It was difficult for me, but I admired the role playing. Especially hers. The players all applauded me for not losing my cool.