A heavy bike actually reduces stability because it's harder to muscle it around with your body. Try doing a trackstand on a motorcycle. When I was learning to ride a motorcycle I tried that just out of habit as the motorcycle wobbled at low speed and quickly ended up on the ground.
Originally Posted by
bike617
Just to address this point: I actually liked the extra weight of a Mobiky when climbing hills --- I tried a hill while trying out the bikes at Mt Airy cycles. The extra weight lowered the center of mass and made me feel more stable.