The 16GB is only there to make you buy the more expensive model
>Sometimes the mere existence of the base model causes some problems that can't be fixed with the existence of an upgraded option. This is a consistent problem in an enterprise environment. The base model is always the one purchased more frequently whether through BYOD or enterprise owned devices. This means that support staff has to spend a lot of time working with users to manage space.
It makes a whole lot more likely that the base model is just to get you to upgrade to the 64GB at this point.
It's the same with the European cars. BMW or whatever will sell you (in this country) a tiny underpowered four-cylinder engine for $N. If you want the four-cylinder engine with more power it will be $N+10K, if you want a six-cylinder engine that doesn't feel sluggish it will be $N+20K, and if you want something that actually feels as fast as the car looks it'll cost you $N+30K.
Meanwhile you can buy a fast engine in a crate for about $5K.