In System 1.7, you can have subfolders and other files, but it's only the documents browser that hides them. There was a time when I made subfolders in System 2.0 and downgraded to System 1.7. In TI-Nspire Link they still appeared, but I couldn't manage them on the calculator.
It would be nice to get Doom to work in System 1.7 though. I can't get Ndless to run on System 2.0 and 2.1 (It just freezes with two horizontal bars of random pixels).