I have seen that many Japanese people avoid meeting friends when they are troubled. Where I was born, it is common for us to look for a friend to talk to, when there was trouble.
I think the definition of "hikikomori" is a bit hard nowadays. If someone shuts himself at home but interacts with people using SNS, or plays games online, does that count?
I think the main concern for the government is the chance that these people might go crazy and do something like the Akihabara killings. But I am not really sure if there is any good data to support this.
My main question is "how are these people supported?" Some of them must be a huge burden (and worry) to the parents.