Bingo. The Stinger brings a new market into their USA dealerships. I don't dare go to a Kia dealer on a Saturday because they are packed selling Optimas, Souls or whatever. All good cars, but not what interests me. The fact that Kia has a demographic, like me, wanting to look at (and buy) their product means it will stick around. Like others have noted, it takes time to build a market share in new segments.
Unfortunately a lot of the Stinger market is about image. Do you honestly think most BMW/MB/Audi owners buy the car for the way it drives? No, it is image. Once a Stinger shows up at the country club/law firm/accounting firm/doctor's parking lot, people talk, look, ask questions, get interested.
The biggest hurdle Kia will need to address to really get Stingers and possibly the K900 moving is the buying/dealership/ownership experience. Part of the image of the luxury brands is the ownership experience. Nice loaner car for all service appointments, nice lounge if waiting, free car wash when you stop by, professional well trained technicians, no questions about warranty or quality defects of the vehicle. These are expectations of the Stinger market and valid expectations if you are buying a vehicle with a MSRP of 50k+.
The Stinger is a great car - same level as the upscale market it competes with. But it takes more than a great car, it takes image/perception, to sell high volumes in this segment.