Schwinn and several other American makers recognized a couple of years before WWII that "light roadster" or "sports touring" bicycles were proving to be popular in Europe, particularly in Britain. Those bicycles usually offered forward-facing rear dropouts, cable brakes, a choice of various hubs (the three speed Sturmey Archer K or AW is the classic), 26 inch wheels, side-pull caliper brake sets, and a more compact frame than a 28-inch wheel rod brake roadster. The English light roadster designs, in particular, tended to take what we would recognize as their early-modern well before Schwinn began making the New World.
By the late 1930s, the American bicycle market was heavily slanted toward children riding balloon tire bikes. The balloon tire bikes had revitalized a market that was not doing particularly well up to that point. The bicycle manufacturers in the US hoped that cycling would catch on with American teens and adults - that more modern bicycle designs inspired by the light roadsters of Britain in particular could revitalized adult cycling the way the balloon tire cruisers had revitalized the youth market. British bicycles had also been coming into the United States, particularly the Hercules, Phillips, and later the Raleigh bikes.
There certainly was some market for the bikes, but it proved to be disappointing compared to the sort of boom that the balloon tired cruisers had done for the American youth market. The real "boom" in adult cycling in the US would have to wait until the late 1960s and early 1970s. That boom provided quite a boost in the sector of adult riders who sought serious sporting, touring, and commuting bicycles.
The early light roadsters from the US makers we see today are leftovers from a hope the manufacturers had that they could expand the bicycle market into older teens and adults who wanted serious commuting or sporting goods. In that sense, they're the "odd men out" - too late for the cycling boom of the late 19th century, but too early for the boom of the 1960s-70s.