You would think that Apple must incur costs taking these units back so often. It seems fairly rampant too with many people exchanging them for various reasons. What I'm getting at is wouldn't it end up possibly cheaper in the long run to just do better product testing ahead of time?
Nearly 50% of the sale price is pure profit for Apple. Unless 50% of the people who buy an Air 2 return it (and I doubt the actual number is anywhere close to 1%), Apple will still make tons of money on the iPad Air 2.
Not to mention they are minting money with the iPhone 6 and 6 Plus so they can afford a few hits on the iPad.