A question remains: How did these idiots manage to get the most primitive technology in the first place and how stupid are we that we've not yet managed to get interstellar technology without having to invent it ourselves in the first place?.
Simple. They aren't idiots.
Im finally listening to the Mission Log podcast. A few months ago I listened to their review of the TNG episode with the Packleds. Their conclusion or opinion was that the Packleds are really masterminds and this stupid act is an act that lulls unsuspecting targets into a false sense of security. They've done this con for a long time with much success.
If course, that's not exactly how LD presented them.