So you are saying that 95% of people never open the file explorer, copy files, renaming files, generating a pdf file and have it emailed to someone.
Okay, you can give up this important feature. You are also giving up productivity. This is your choice but not most people's choice.
The inability to manipulate files is a major drawback of iOS as compared to a desktop OS - this is a well known fact about iOS.
Well, you may use iPad mainly as a content consumption device plus some basic content creation. You cannot manipulate files. Then your use cases would be very limited. At the end you still need to have a PC/Mac to consolidate your files.
Users expect to do everything on a productivity tablet, instead of just basic content creation. I can use my Surface to do all sophisticated tasks, thanks to the ability of manipulating files.
And iPad? What if the app does not support Cloud? I need to email myself a copy of the document, open it with the app, edit it, and email the modified document again. Doing this is very stupid. Maybe you like this. But many people hate this.
There are too many use cases that people need to manipulate files. You should know that very well.
Seems that you don't need a PC while many people still need it. And you described this important feature as something only a minority of people would use. Seems that you are the 5% of efficient people who can work efficiently in such a limited OS (iOS). Many people are not as efficient as you.
There is just no room for debate on iOS against desktop OS (Windows/Mac) as far as file management is concerned. And this is just one of the limitations of iOS as compared to a desktop OS.