While I agree that writing has its limitations and that a lot of non-written info is lost, I don't think the written part is the problem.
For if that were the case, YouTube would be a thriving beacon of clarity, when it clearly isn't. And as an effective counter-example of a only-written-yet-successfulish-conveying-meaning you have HN.
So no, communication by writing is not the problem.
But HN seems to be the exception, rather than the norm. Whether that's because of good moderation, or demographic, or something else, I'm not sure.
It's certainly easier to get the 'road rage' mentality when writing, than when conversing in person. As well as losing information, communicating through text makes it more difficult to relate to other people as people. It can lead to people behaving in terrible ways that they'd never do in person. Road rage does a similar thing: ordinarily nice and well-balanced people can be enraged by other road-users, but would never have such a response walking down the street. (This was captured rather brilliantly by a comic [0].)
I wasn't the only one who was surprised to see that real-names policies (such as on Facebook) fail to get people to behave themselves.
For if that were the case, YouTube would be a thriving beacon of clarity, when it clearly isn't. And as an effective counter-example of a only-written-yet-successfulish-conveying-meaning you have HN.
So no, communication by writing is not the problem.