On the other hand, there is a lot of games and educational programs that produce speech, sound effects and 3D sound. Hearing can be regarded as an additional information channel, largely independent from vision.
People use to solve problems in teams, so a kind of communication within a team is needed.
Vision is often obstruct by watching computer screen. Hearing is then the only channel that is free for communication. On the other hand, computer games attract as much attention as possible using all human senses to entertain the user. There are some exceptions from the general rule, that I proposed above. People that use their vision for other purposes than watching computer monitor may prefer to hear to information output by computer.