Men writting as Women; Women writting as Men

In an online research that I made, I founded the following information of men writting as women and conversely.

Daniel Defoe

Defoe had already impersonated one indomitable woman, Moll Flanders, when he produced The Fortunate Mistress, a novel often called after its anti-heroine, Roxana, who tells the story of her life as a Restoration courtesan. She offloads any children, but is punished when she finds herself pursued by her own daughter.

Roddy Doyle

Doyle's The Woman Who Walked into Doors tells of an abusive marriage from a woman's point of view. Paula is married to charming petty criminal Charlo, who oscillates between tenderness and violence. Partly a story of sexual intoxication, it certainly does take us into the bedroom and gives us the pleasures of love from Paula's point of view.

What are the benefits and limitations of this approach?

I thing that this situations of a men writtin as women gives benefits, because it show the way a men thinks that  a women might think (or conversely). Also it a different way of writtin, so I think is kinda interesting in many ways.

Why do other authors, like McEwan, take the opposite approach?

Because as I said before, they want to show the way they think that women think, by a women character. Also it can be, bacause they think that the story would be more interesting if the narrator is a woman, than if a man tells the story.