Queens and Brooklyn can't get up to that level of density unless we build more transit lines. This is very difficult to do in NYC. Without additional lines, the city's road infrastructure would not be able to handle the additional traffic.

I think the author's point is to build more density along existing lines. Many stops in Queens and Brooklyn already have 3-5 storey development around them. Thus, build higher in those areas.

I agree that 3-5 storey development is a nice density for living in (I choose to myself). But practically speaking, spreading that zone wider in NYC, without any sort of transit plan, is not possible.

You might not like walking through it, but I think Long Island City is a success story for this model. Thousands of workers, who otherwise would've been driving up rent in Manhattan, decide to live near the LIC transit hub in high rises, and I think the city as a whole is better off because of it.