To be fair, there will probably be (unauthorized) third party SSD replacements, and USB3 allows much more flexibility with external upgrades.

I imagine it adds $200 on to the cost, because they will feel the need to top up the extra 8gb to future proof themselves.

Yeah. It's also disappointing that the high end model still only has 8GB standard, but that way Apple guarantees that you have to order through them if you want 16. I'll still do it, because by all accounts the display really is that good. It will likely be my last Apple hardware purchase, assuming that in a few years other PC manufacturers have realized that Apple is on to something with their brilliant strategy of making displays better instead of worse.