There is a trade-off between wanting people to store as many types of file as possible, and not wanting to get associated with some of those files. It would not do for Microsoft to get a reputation as "the company that helps wankers store their porn". Some people would use competitors instead because they object to porn, other people (and businesses) would use competitors so as not to associate themselves with porn either.
Why does this reasoning apply to file lockers but not to e-mail? I have no idea.
But these machines are not machines owned and operated by Microsoft. If a (non---porn using) vicar stores his Bible study notes on his PC, he knows they're not going be sharing a disk with porn.
There is an ick-factor here, I'm not saying it's rational.
What is the big problem with Porn anyway, especially the US where almost all Internet Porn comes from. Studies have found nearly every man consumes it, how can there be a stigma to it?
Well of course we have to protect the children and they shouldn't find it accidentally, then publishing should be the only issue here.
Porn is associated with wanking, and wanking is stigmatised even though presumably most men have been wanking for far longer than most men have been using porn.
Porn is also associated with prostitution, which is stigmatised as well. And some men feel that although of course there is nothing wrong with the porn they watch, the porn some other men watch leads the featured actresses into prostitution.
And some men watch porn even though they feel it's morally wrong (and morally wrong things are stigmatised). They just don't have the self-control to stop themselves. (That makes them hypocrites, but most people are hypocrites one way or another.)
I get that "protect the children" is an overused slogan these days, and not just in relation to adult porn. But it's far from the whole story.
(n.b. I'm trying not to argue about what should be, I'm trying to talk about what is.)
Not only nearly every man but a large minority of women too (perhaps soon to be a majority).
I keep waiting for a porn-in-the-workplace case to come up where someone brings up the fact that we are approaching gender parity in porn consumption, and watch courts start to grapple with that.....
Why does this reasoning apply to file lockers but not to e-mail? I have no idea.