[TulliusCicero]

Bikes are good/useful in a number of ways. They're a form of individual transport, like walking or driving, with the advantages that that has over public transport -- namely, less waiting, point to point, not beholden to a schedule that might not match your schedule -- and they slot in nicely between walking and driving as a compromise between the strengths and weaknesses of both. Much faster and longer range than walking, more cargo capacity, but still much cheaper than driving, and without most of the issues cars have with things like generating noise, pollution, and danger.

Bikes are also healthy for people, and they're certainly more space-efficient than cars. Oh, and they're vastly less expensive for the city as well; building subways is enormously capital intensive, and buses have high ongoing operating expenses. Good quality bike infrastructure isn't exactly cheap...except that compared to high quality car or transit infrastructure, yeah it is relatively cheap.

So, altogether, replacing car space with bike space makes a ton of sense, especially for a city as dense as NYC. Sure, bus and subways improvements should happen too, but there's so much car space that's wasteful, and bike stuff is so cheap, that it's really low hanging fruit. No good reason not to develop it.