Maybe they didn't want to make too big of an investment here until they had some supporting sales?
...but by cutting corners in their launch, they also limited their sales.

Nah.

In the end, Americans are cheap. We don't want to pay a fair price for a quality product. We prefer to pay less and tell ourselves that it's "good enough" until we learn the hard way that it's not. We're slow learners in this respect.

To me, the target audience for a Brompton shouldn't flinch at the initial cost, since it replaces a car or a lot of public transit fares. But we inevitably start shopping cheaper ones. After all: why pay $2k when a used $200 one will do the job? As noglider said elsewhere: most city commuters aren't "bike people", but just on a bike because it's the mode of transit that makes the most sense for their commute.