To see them as necessary is really just the nature of humanity calling us into its depths, though we try and fight it, it's still there. Throughout the novels I have currently completed, about 80-90% have at least on of "those" scenes, and as long as it as seen as lets say a "reward", the payoff isn't particularly a bad thing. I have seen at least a few bad "rewards" in the sense of a blatant, sex-crazed, scene of lust, but really, if the scene was there as a filler of information about the love between the characters, I see no harm in it. I am however a fan of the more cute and vanilla relationships, which may give you one scene as proof of the true love the two may share on a deep, emotional level. This I believe applies to the real world in a sense as it's not an essential thing, but when it happens in a way that strengthens the love between two people, there really is no reason to deny it.
I may just be going on a slight rant here, and possible off topic so forgive me.
I just see H-scenes as a way to express the relationship in a way that most people can understand, rather than reading the beautiful lines and looking at the amazing artwork displayed at any other romantic scene (i.e. Kissing, hugging etc.).