The majority of your stopping power comes from a front brake. I can see the "law of diminishing returns" coming into effect with your current braking system.
I would never want to be without front brakes myself but over the years I have learned how to use them to their full potential without going over the front bars and they have saved me many times.
"I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it." - Thomas Jefferson