My Two Cents On This Thread
1. Regarding Battery: People here are reacting to (a) the smaller battery, and (b) the reported less battery life on the part of the reviews for the iPad Air 2. Things to consider: these reviewers were supposed to run tests that were the same between the iPad Air and the iPad Air 2; they are largely not real-world use case scenarios. That being said, yes, it appears as though the battery life is diminished a bit. Is it enough to notice or be inconvenienced. Judging from the reviews I've read (pretty much every one that MacRumors linked to earlier today), I'm inclined to say no.
2. Regarding those who are pissed off about the battery life being lesser, it is a valid complaint, but it seems to be more a matter of principle than a practical concern, given that reviewers didn't seem to indicate that the battery life was so much worse that it'd be inconvenient or otherwise noticeable. That said, no one would complain if, internals, camera, and laminated display all aside, Apple left the form factor and the battery alone. .04mm isn't so much of a difference that it's worth that kind of thinness.
3. Regarding those who prefer the thinness, the original iPad Air was a huge improvement in weight over the first, third, and fourth generation iPads, as well as the iPad 2. It made it easier to hold. The thinness lends to that. Making it easier to hold means that people will want to hold it for longer. I get that. However, Apple has long had a habit of stunting performance at the expense of thinness, and when there isn't really a need for it, it's sort of stupid. At this point, with the iPad Air 2 and the iPhone 6 family, the iPad Air and iPhone don't need to get any thinner. The MacBook Air and MacBook Pro both are at that point now as well. The iMac especially doesn't need to be any thinner. At this point, they're all so thin that to make them any thinner reduces comfort, reduces thermal reliability, reduces computing power, or even combinations thereof.
4. As I understand it, "the secure element" is a part of the A7, A8, and A8X SoCs. That is where your fingerprint is stored, and it would make sense to have your cards stored there as well. As for why an NFC chip is present on the new iPad Air 2 but not active, I couldn't say. It does seem like the ideal thing to have as a mobile POS for iPhones that are using ApplePay to pay. While it would be silly to use your iPad Air 2 for ApplePay, I don't think it'd be THAT silly, especially if you carry your iPad Air 2 everywhere. Similarly, and moreso, the size of the iPad mini makes it substantially more convenient to use at a POS for ApplePay (especially given how close it is in size to the Plus-sized iPhones).
5. Apple is not going down, and Steve Jobs would've totally endorsed the iPad Air 2 as the natural successor for the 9.7" iPad line. Saying that this is the sign of the end of times for Apple is just silly.