It's a textbook example of price discrimination on Apple's part. They know that the 8/256 model is not enough for several classes of Pro users, so they can sell

It's a textbook example of price discrimination on Apple's part. They know that the 8/256 model is not enough for several classes of Pro users, so they can sell the 16/512 model at a premium (while increasingly locking down their devices to prevent after-market upgrades).