If you look head-on at any old USB connector, you'll see that it's basically a rectangle, just extended into the third dimension... a rectangular prism.
So... what exactly would any sort of 4D plug look like? Would it be like a cube extended along the w-axis that just looks like a normal cube until you rotate it? Or would plugs possibly be tetrahedrons from head-on, until you saw that they were actually tetrahedronprisms? And how would it connect to something to transfer information like a 3D USB device? Wait, are there even electrons and atoms in the fourth dimension?!? What about quarks?!? Leptons?!?!? Gluons?!?!?!?!??!?!?!? WHAT IS THE EQUIVALENT OF A BYTE IN THE FOURTH DIMENSION‽‽‽‽‽
Uhhh.... well, let's just keep it simple for now...