I am getting an HTC Radar 4g, but have a question regarding the omission of the gyro sensor.

People on a few forums have been angry that HTC left out the gyro sensor for the Radar 4g to keep the phone as cheap as possible while meeting Microsoft's standards of Windows phone, but I have one question, what is the gyro even for? I rememmber Apple touting the gyro back when the iPhone 4 was released, but what is it used in? Does a game like super monkey ball require it, does the sensor matter? Thanks.