I always wonder about this because I always here stories of how the workforce is Japan is terribly inefficient unless they're part of a huge company (i.e. Sony). The inefficiency was generally related to lack of work during core work hours. Then you hear about things like this; people work too hard
In the end, this is terribly confusing, so my guess is, suicide probably has something to do with Culture, more than anything. I've been told by Japanese students that sometimes parents/older people commit suicide so that they are not a burden to their kids...