The extended warranty is insurance. What this means is that, yes, you're reducing your risk exposure to unexpected mechanical maladies down the road, but don't forget that they wouldn't sell them if they weren't profitable. What this means for you is that the odds of you suffering sufficient repairs to justify the extended warranty (i.e. total cost of repairs exceeding the amount you paid for the warranty) is fairly low by design. If it wasn't, Kia would either increase the price for it until the odds and profits were in their favor or they wouldn't offer it.
Like most insurance purchases, it's all a matter of risk and how much of it you can afford. If you're fairly comfortable financially and can save up enough to cover a catastrophic repair ($2000+), then don't get the extended warranty, save your money, collect interest on it, and count your blessings. On the other hand, if you don't have that kind of cushion, you'll want to shield yourself from the risk by paying the known cost of the warranty.
For what it's worth, I purchased the extended warranty on mine. Then again, I put over 30,000 miles a year on my car, so I wanted to shield myself from risk for as much of the car loan as possible. By the sound of things, mileage isn't a worry for you, so it'll ultimately depend on what the life of your loan is (it's difficult for most people to cover a car payment and a catastrophic repair bill at the same time) and how long you wish to keep your car.