Well, the point is, to get to a green space, you need to get in a crowd in the first place. You cannot avoid them that easily. It's like you get double-punishment before the reward.

Tokyo is simply a city that is OVER-capacity, not by a factor of 1 or 2, but 10 or maybe more. If the train is 10 minutes late for any reason, any station would be filled with people on the platforms you can cross through it anymore. That says a lot. I feel New York is way more livable, from what I can compare.