this is nothing new, but i'll type it anyway before hitting the sack...
So when would anyone want to use the rear only and why?"
among other times, when navigating through obstacles at very slow speed (in a parking lot, or when lane-splitting, for example). my msf instructor - a 20-year veteran of the florida motorcycle highway patrol (h-d road kings) - made it very clear to us that the back brake helps keep your bike upright in tight, slow turns. YMMV.
"Does the type of bike matter?"
yes. i would take an advanced training course from the MSF to get instruction on correct braking techniques for your specific bike.
So when would anyone want to use the rear only and why?"
among other times, when navigating through obstacles at very slow speed (in a parking lot, or when lane-splitting, for example). my msf instructor - a 20-year veteran of the florida motorcycle highway patrol (h-d road kings) - made it very clear to us that the back brake helps keep your bike upright in tight, slow turns. YMMV.
"Does the type of bike matter?"
yes. i would take an advanced training course from the MSF to get instruction on correct braking techniques for your specific bike.