A roller ball tip is often preferred over a marshmallow tip on a mobility cane for the visually impaired due to its ability to provide greater sensitivity and precision. The rolling mechanism allows for smoother and more consistent tactile feedback, making it easier to detect surface irregularities such as cracks and bumps. Additionally, the roller ball tip is typically more durable than marshmallow tips and can last longer, making it a popular choice for those who rely on their cane for everyday mobility.