Absolutely agree, blows my mind that there is no OnClick for a folder/item 

To have all the folders, and their children, as well as the contents of those folders, all come back in an API call for example is not always practical. 

What if the user has 1000's of folders with 1000's of images/documents in those folders? 
That call will take a long time and the UX will be bad. 

To allow us to say, on folder click, get contents for that folder and refresh the FileManager, that would make a lot more sense with regards to our use case, and I would imagine, quite a few other peoples use cases too...