Different type of game require different levels of privacy. On these pictures taken in Seoul: compare the lonely gamer in arcade-game row to the comfy-door-augmented karaoke arcade game. The possibility to close a door surely allow more privacy for shy karaoke players

At the same time, read about this topic in The Economist:

"as other aspects of gaming become more realistic, from high-definition graphics to vibrating controllers, manufacturers sense an opportunity to offer dedicated gaming furniture, controllers designed for specific gaming genres and new types of fancy screens."