For me, two reasons:
1) Two independent braking systems means you always have a backup if one fails
2) When braking, the mass of the bike + rider is moved toward the front of the bike, due to inertia. This has the effect of diminishing the stopping power of the rear brake and increasing stopping distance - a problem in an emergency.
For me, two reasons:
1) Two independent braking systems means you always have a backup if one fails
2) When braking, the mass of the bike + rider is moved toward the front of the bike, due to inertia. This has the effect of diminishing the stopping power of the rear brake and increasing stopping distance - a problem in an emergency.