I think that people may liken the romance genre to porn because both appear to set unrealistic expectations, not necessarily because critics see them exactly alike. Men watch porn because they want to see "perfect" beautiful women without their clothes on, doing things in movies that most women do not do. Women read romance because, often, the male interest in the stories are strong, yet tender. Maybe an unrealistic match may be made (a "geeky or akward woman is the love interest of a hunky guy, who realizes that what he is looking for in a woman is what she has to offer inside, although he does find her asthetically beautiful, as well). The man knows what to do to make his partner happy, and does it because he wants to, not because he is expecting anything in return! Both forms of entertainment meet the need of fantasy in either situation, but neither promotes realism with what you may have for a partner in your life. I would argue though, that with the romance genre, women are not seeking something that is UNOBTAINABLE or unrealistic in that, with the women being portrayed in porn, one cannot create a mold and form their ideal partner. In romance, there are not things (in a non-paranormal sense) that are portrayed that the "hero" does for his partner that a man could not do for his partner in real life. Sure, we may not all be able to, say, marry bachelor billionaires, but the way that he loves and cares for his partner is not something that is unachievable by any man.
Honestly, the scariest stories in real life are of shocking things that our seemingly "normal" neighbors do behind closed doors. I believe that you can think that you know someone, but never truly know what evil may lie beneath the smiling exterior. What could be more frightening that that?