Tim, saying something is built as cheaply as possible because it's a kit or weighs half what another boat does is foolish.
The 'cheaply as possible' theme came from the catalog -- Luger was very proud that their boats were so inexpensive. Every page seemed to emphasize this 'feature'.
For instance, the first paragraph in that old brochure says:
"The Tradewinds compares with like-sized sailing craft priced up to $25,000, yet your Tradewinds saves you about half their cost."
In general, you're right that a boat weighing half that of another isn't necessarily a more cheaply built boat. For example, a fancy carbon-fiber/kevlar epoxy cored hull that is half the weight of a standard fiberglass polyester solid laminate hull is much more expensive to build -- but Luger wasn't using high-tech materials. Luger used the same materials as Catalina: polyester resin, E-glass and plywood. If their boat weighed half as much as a similar sized Catalina, it only used half the material. That means much less strength.
And being a kit doesn't necessarily mean a poor boat -- half the Westsail boats were sold as kits and their resale values are considerably above many contemporary factory built boats. However, a kit builder can't create something better than the underlying components he's working with, but he can certainly make something a lot worse.
The Luger seems to sail great from what I've heard. When you have people trying to sail around the world in homemade 10 foot boats it's probably wise not to dismiss kit craft as being cheaply made junk.
The Luger 26 being half the weight of the Catalina 26 with similar waterplane area is going to give much quicker, 'corkier' motion. When you consider how little ballast the Luger has and how high it is mounted, the center of gravity of the boat is quite high which gives little stability. I expect the Luger is at the edge of the design envelope for this size of sailboat, and not on the good edge.
I'm afraid I don't quite get the connection between people who want to sail around the world in a 10 foot boat and whether Luger kit boats are cheaply made or not. Sorry.