I agree that using a stroller in Tokyo is more trouble than it's worth most of the time, but I still see people using them everywhere. If you don't see a lot of strollers it's probably because you are in an area where people don't take their kids, e.g. a CBD during a weekday. Walk around Tokyo Midtown or a large public park on a weekend, or go out to the burbs on a weekday, or better yet go out toward Disney, and you will see strollers all over the place. Also noisy kids and rude parents.