At this moment in time, your ship is the only thing you can use to store anything in. Well, not strictly true, Modules can be stored - to a point, and Ships can be stored - without cargo. This is normally fine for the day-to-day pew pew stuff, but pretty soon, it starts to become a problem when a player wants to do other things. It's especially a problem for anyone interested in Trading. It's also a problem if you wish to hop from one ship to another quickly - without selling