Good job! It would be interesting to see what a straight off flat draft to your measurements of this pattern would look like, although that curved hook shape might be tricky. Looking forward to seeing the next installment.
The patent is assigned to Thomson Langdon and Co, of New York, who marketed Thomson's Glove Fitting Corsets. Interestingly, this firm, according to Valerie Steele's Corset: a Cultural History, is associated with tightlacing, having received a favorable mention in http://books.google.com/books?id=JkMBAAAAQAAJ&pg=PA6&dq=thomson corset crinoline&hl=en&sa=X&ei=ZuoVUZCsCZC00AH myoHwCQ&ved=0CDgQ6AEwAQ#v=snippet&q=thomson&f=false
Interesting article! I'm always very happy to read about these patents being made up -- I think they're excellent material for thinking and learning about seaming and shaping, even though some are obviously more successful in that respect than others.
However, your reasoning that "[...] many home corset-makers would have been intimidated by looking at a vertically seamed pattern with no gores at all" seems strange to me. True, "[...] the corsets that I have seen constructed as one rectangle with gores have all been rather crude and homemade", but that doesn't automatically mean that all home-made corsets were crude rectangles with gores. Home sewing magazines such as La Mode Illustrée / Harper's Bazaar / De Gracieuse had been around since the 1860s with far more complicated corset patterns than the average crude rectangle. Admittedly, these magazines were probably not available to the lowest classes, but I think in general sewing skills were quite a bit beyond what they are today.
I'd agree with urbanseamstress above, and offer another possibility too. Maybe its simplicity wasn't just for ease of use, but also for speed - could this, in fact, have been meant for potential mass production?
However, it's also interesting that you say the corsets you've seen with this type of pattern tend to be crude, Luthien, so perhaps you're right.