What is the purpose of the channel in my seat? What is the purpose of the channel in my seat? Is it just for comfort or does it have some medical benefits?
The purpose of the channel in a bike saddle is to reduce pressure to the perineum, which can cause numbness and other long-term problems. This is a matter of both comfort and health, although not everyone is affected. Individual body type, saddle design, bike fit, and riding style work together to make saddle fit a very personal issue.

On a related note, some of the worries about erectile disfunction seem to be overstated, though this is still an open area of research. See: 
Saddle Seats and Erectile Dysfunction - The myth Exploded.