The Air 2 already had one of the best tablet displays on the market. The Pro, with Pencil support, keyboard support, better speakers, more base storage, the best screen available anywhere, etc. is well worth the minor price bump. If it's not, well then lucky you, Apple dropped the price of the still excellent Air 2!
I whole heartily disagree:
1) Pencil support is worthless w/o an additional $100 Apple Pencil. Further, it's to Apple advantage to encourage users to buy another accessory. Why should any owner have to foot the bill to include support? That cost should at least be sunk into the cost of the pencil, not the device, unless Apple is going to open the feature up to 3rd party manufacturers -- then put the tax on the 3rd parties who can then push it off on consumers through their product.
Imagine if Apple included camera flash support in iPhones, but not the flash itself -- that was an extra $100. Would you be cheering how awesome the iPhone was because it could support a camera flash?
2) Keyboard support: Honestly? Before Apple made keyboards a jillion and one other companies did. There is nothing wrong with a b/t keyboards that pre-date the Smart Connector. And again, Smart Connector benefits Apple mostly.
3) Better speakers: "Better," is a meaningly term here. They are still button sized. I don't think anyone is going to give a presentation on their iPad with these speakers, better that they may be. The Air 2 speakers are not that great. Apple owed it to customers to do better. But bottom line here is that speakers cost pennies. I don't see where a $100 bump comes into play.
4) More base storage? Only if you are a Kool-Aid drinker. The previous $599 Air 2 WiFi model had 64GB. So for the same $599 consumers are losing 32GB. Keep in mind the wholesale cost difference between 32GB and 64GB is $1 or so.
5) Best screen anywhere. As I previously said, the screen on the iPad 3 was miles ahead of the iPad 2's screen and there was no price increase. So I'm not sure you how justify a price hike from a good retina screen to a better one when Apple didn't raise prices from non-retina to retina.