http://xkcd.com/871/
"I usually respond to someone else doing something good by figuring out a reason that they're not really as good as they seem. But I've been realizing lately that there's an easier way to handle these situations, and it involves zero internet arguments."
Do you know that feeling that a song is specifically about you and what you're going through? It's not, of course. The composer doesn't give a damn about you, but isn't it great to feel good about it?
Not all benefits necessarily have to be quantifiable. We humans happen to be emotional creatures. Emotion counts, too. It moves us. Even if it's gimmicky, even if it's tacky. Even if it's for profit. Even if it is a PR stunt.
That's fine, but at least be honest about who you're benefiting. If you want to write a message because it makes you feel good, go for it and be happy. If you are doing so because you think it's helping someone else on the other hand, it's seem like good odds that it's mostly just self-deception.
My point was that, as innocuous as it may seem, a message of support can make a few of the people in distress feel better. Maybe they've been materially taken care of, but there's still something amiss. That's where I believe emotion counts. If you can also donate something, well, even better.
And there is no dichotomy, I think. I'm glad we can both help and feel good about it.
Hard to know what zyb09 really meant by his/her comment. It's the sort of comment that I don't like to see on HN, since it states a vague opinion without offering rational. If zyb09 had provided reasons as you did, it would have been a different story.
Although, if this is to be believed even the donations may not be as beneficial to Japan as I would have thought:
http://www.nytimes.com/2011/03/16/world/asia/16charity.html