There is a difference between writing "other" for the other and writing other for those like you. I was considering this notion of writing other-- writing from the perspective of someone who is not like me-- and realized I haven't done it all that often when the audience is able to authenticate my writing. Regardless of the topic, it's scary to have an expert say, "You got it wrong." Being told that I got it wrong by someone who lives and breathes the life I'm writing is not only scary, it's embarrassing and shameful. It's an insult to the "other" that I am writing about. So perhaps that's why I don't do it very often.
I have written from the male perspective dozens of times, but I have written it for women. In romance and erotic romance, the audience is primarily women. Writing alpha males comes from a place in me that likes the idea of alpha males but would likely run screaming if I were in a relationship with one. On the page, my male characters are written with an audience in mind-- and that audience is me, not a guy who served twenty years in the army and rides a motorcycle, like the character I'm writing. That guy--reading about the fictionalized version of himself--might laugh at my portrayal. I'm too scared to ask, to be honest.
Which brings me to the point of writing "other"--for me, at least: bringing the reader a fantasy she can enjoy. My "other" writing skews to the female fantasy side of fiction-- male characters as women fantasize about them and otherworldly creatures as perceived by me with no one to suggest my portrayals are inaccurate. I have also written lesbian fiction from the perspective of a bisexual woman with some experience, though I sometimes feel distanced from the experiences of those characters.
I have occasionally tackled a character of a different race, tapping into my own experiences as a minority in various communities. Yet I'm always wary of stereotyping, of being a voice for someone whose life is so far removed from my own. I have not yet written a transgendered character because I don't feel I could do the experience and emotions justice. I believe I have written only one story from a gay male perspective and while I was honored it was published in Ultimate Gay Erotica (from the defunct Alyson Publishing), the story was very much tongue-in-cheek with a fantasy theme and a level of humor to suggest erotic satire. In other words, it wasn't written to be taken seriously as the gay male experience.
I am an advocate for writers writing anything they choose, from any perspective they choose. If an author is comfortable writing the other--and can do it with a level of authenticity--I wish them all the best. But as a woman who has encountered her share of inaccurate and insulting stereotypes written by men who didn't have a clue about the female experience (or even the female anatomy, in some cases), the key word there is authenticity. Like every other aspect of writing, research is paramount when you are not completely familiar with the subject at hand. Never is that more true than when it comes to writing about people who are different than us. I may write fantasies for women with male characters who are too good to be true, but if my audience were men I think I'd have a couple of those men authenticate my work before I sent it out into the world. It's embarrassing to have someone say that you didn't get their experience right-- but it's a hell of a compliment when they say that you did.