Observe the land use maps of Queens Community Boards 6 (PDF) and 9 (PDF), which host most of the Cutoff: along the Cutoff’s right of way, the primary uses are single-family residential, with only a little commercial. Moreover, the commercial development is often very auto-oriented, for example at Metropolitan Avenue. Indeed, the only proposed station with significant dense development is Rego Park, which is on the LIRR Main Line and could be restored without restoring an entire line. Rezoning near the other stations is possible, but why not rezone near existing subway stations first?
Sure, on the map there are lots of single-family residential areas, but if you go there you see things like the Forest Park Co-ops:
When I took this picture I had my back to the fence enclosing the right-of-way. These are dense developments, with hundreds of residents. There's another condo across Park Lane South that used to be a factory. A little further north you see Forest View Crescent:
This massive twenty-story co-op sits right next to the right-of-way; in fact, one of the initial obstacles when the MTA tried to restart service in the 1960s was the fact that the co-op is using the right-of-way for their parking lot. A few blocks north is the commercial development along Metropolitan Avenue that Alon mentions:
There were similar numbers waiting on my side of the street for the eastbound bus, and on Woodhaven Boulevard for the buses going north and south. Just a block east of the Rockaway Branch is the beginning of a relatively dense, walkable two-story commercial district along Metropolitan. Finally, north of there is another area of apartments around Fleet Street:
Because of this, I think the Rockaway Branch would get more riders if it had stops at Fleet Street and Myrtle Avenue, in addition to the old stations at Parkside (Metropolitan Avenue) and Brooklyn Manor (Jamaica Avenue). Between residents going to work and shopping, and people coming in to the schools and shops, there are hundreds of people who currently drive or take the bus or slow train. Rezoning the area near the Parkside station to allow more dense development would bring even more riders.