The window watchers is an intetesting phenomenon, and you have a point in that in a way it’s like keeping useless employees out of the way. However, I would hesitate to say they are actually useless, but rather the labor market in Japan is such that it’s extremely difficult for a good employable person to “hop” jobs. Once hired out of University, which is the main avenue for hiring for the sarariiman, workers have little chance to change jobs. In that atmosphere and culture, it’s nigh impossible to have your window watchers go out and find a job where they could actually be productive. Many of them (most?) are able and productive but the company has moved on to other things, or refocused, realigned, reorganized and these people get trapped.