You pay a lot more for that too. The only reason i can think of is that Apple is going to go hard into VR soon with something like the samsung gear
You dont need a gear like gadget. . . it does it now with just the iPhone in the real world on the screen. Strangely, the iPhone 8 is faster than the more expensive iPhone X.
As for a 50% faster chip, how does that extra cost translate into value for a guy who utilizes the phone basically for calls, text messages, and internet? Now that is the true consumer benchmark;)