Pretty disappointing when you really think about it though.
Right now we've got better quality cameras on the phones which take up more space, better quality video recording, bigger app sizes, more apps, more people downloading/using apps on average, bigger app caches, and an operating system that takes up more space than it used to ~5 years ago. Hardware costs, especially Flash memory, have plummeted.
Yet we've had the same 16GB base storage on the flagship iPhone for 6 years (since the iPhone 3GS).
6 years is an eternity in tech terms. Skimping on storage is such a planned obsolescence move - as much as I hate that term. Get them into the ecosystem, make a lovely quality product, but cripple longevity with a complete lack of storage space.