So why don't I just get a Honda Civic Hybrid instead of the Insight?

For starters, it's almost a guarantee that the Insight will be less expensive than the $23,650 Civic Hybrid. The Civic Hybrid is slightly larger and more powerful than the Insight, but it actually is rated 1 mpg better combined than the Insight (though it doesn't have any of the gadgetry the Insight has to help your drive more economically). My guess is that people who want to drive something that "looks" like a hybrid will gravitate to the Insight as well. At a presumed cost much lower than the Civic Hybrid, the better question is why wouldn't you get an Insight?