Google Buzz was tested by 20,000 Google employees and still launched with a feature that generated loads of complaints until the feature was dropped.
“One of the features of Buzz was that it would automatically connect you to people whom you have emailed in Gmail. On the surface, a great idea. A slick idea, which worked really well with 20,000 Google employees. […]
Google employees are special. They’re very carefully selected by the company. They have skills, abilities, and lives that are very different from most people outside Google. […]
By not using an outside sample, Google ran into a major interaction design problem. About as big as it gets. […]
Google miscalculated when it assumed that everyone you email is someone you want to share things with, and that you might want those people connected to one another. In a work setting, this might be true. In a closed community like a corporation, this might be true. But the outside world is much messier.”
Read on: You are not your user. No matter how good you think you are
Also: You are not your user
