Re: "The lowest of the low phones comes with 16GB nowadays, and I only use 10"
Don't draw conclusions about others from your own lack of using the full potential of your tiny, pocket-able computer.
I have 20 GB of music, 32GB of about 7,200 books ranging in subject matter from technical, engineering to medical and also a few novels. Then a few movies, concert videos and downloaded Harvard lectures from Youtube and other tutorials for another 30GB. Beyond that, I take a lot of pictures and video with the phone, which also tends to grab space, so there isn't that much room left on my current 128GB MicroSD.
I can access all this without an internet connection, whenever I need it, as its always in my pocket.