Hi callum, I think it's important for male writers to contribute thoughts to this. I know that I've actively sought out some male writers' opinions in the past and become good friends with several male slash writers(admittedly it's a small group in the slash community) and have benefitted as a result. Not to say that male writers or women writers have a single opinion -- certainly it varies with the individuals. What I saw in the LOTR fandom was that male writers were welcomed and honored, so I'm sorry if you had a different experience.
My strong feeling is that the lines between genders are much more fluid than our digital black and white society would like to believe and that we react much more similarly than differently. I'd be curious what you thought about it? Why do you think women write slash?