Moreover, more influential people who very strictly value their time and privacy (Matt Cutts for instance) might not be comfortable having an open avenue by which anyone can contact them.
More importantly, if you have someone's full name, there's a reasonably high chance you can find a proper way to contact them - provided you are determined enough to do it.
And if you don't want private msgs, just turn on a flag to disallow it.
@Others, If I really want to contact someone on HN, I can definitely find their email ID. But email takes it out of the HN context and makes it much more formal.
And we could always have a PM disabling option.
I have always liked HN because it is simple, no-frills, totally focused on one thing.
I got the hell away from Digg because of its push towards being "social." While messaging isn't that big of a feature I feel that if people here want to find/contact each other they will.
We're all pretty smart individuals if we want to contact/find someone we will be able to if they want to be contacted/found.
The email address in your profile is not visible to other HN users. If you want people to see your address, put it in your "about" box.
Yes, it's true that "if you want to talk to somebody badly enough, you can probably hunt down their email address" but why add friction to the process? Ok, I get the folks who uses it as a filter "if you're too lazy, or not smart enough, and can't find my email, I don't want to talk to you." Fine, but I doubt most people feel that way. And that just argues for making the feature optional (that is, let users set a "receive PMs (Yes/No)" flag in their profile.
Iuguy makes an interesting point though:
Besides, you can always reply to someone's comment and ask for a way to get in touch with them.
The problem with that, as I see it, is that such a message is usually going to be (relative to the rest of the conversation) off-topic noise that nobody else cares about.
Besides, there's email if I wanted it to be so.
Let other people decide that. I can't think of anything anyone would want to ask me, either - except that once someone wanted me to get in touch to talk about my university. (I think I forgot to contact them. Sorry.) I still can't think of anything else I might be asked, but there might be something.
If you actively don't want to be contacted, fair enough. If you just don't think you will be, it doesn't hurt to be available. (But yes, email is sufficient.)
Then do the exact opposite.
Would Digg add direct messages?
I'd like to see tags on stories (restrict to membership of certain timelength and karma) with their own RSS feeds. But I know that's unlikely to happen.