Because UE4 (not UDK, thats exclusive name for free version of UE3) asset registrydoes not analize classes on in source directory, what you see in those folder is data from reflection system registed by generated code in your module (and all other modules in the enigne) and won’t be updated until UnrealHeaderTool won’t update that data on recompilation and new version of module get loaded.
You need to remember those folders been primery made for Blueprint only users which are used to asset content browser workflow, to access C++ classes without needing to create blueprint just for that, C++ is not ment to be used as assets. So in other words you should not care much that folder structure there don’t happen live, it’s irrelevant for blueprint users.
Classes should be viewed by there inherence tree and this is what “Class Viewer” is for, you can find it in Windows->Devlopment Tools, it works same way as content browser, you drag and drop placable actors from there. If oyu intentivly use C++ classes you should use “Class Viewer” insted