You've completely missed the point.
It's not about stopping people from hearing or seeing content from the game.
Why would I want to do that?
The reason .ogg is mentioned is because it appears to be the only type of file (so far) that can't be renamed and still recognised.
There are various files that hold different information for the game, and if all files were able to be renamed to the same extension, but still recognised from the game, then it might deter people from messing with any of them.
I'll give you a couple of examples of why this is important.
Several years ago I wrote a scenario for the trainsim Trainz.
This was written in the built-in TrainzScript language (java-like), and although the scenario itself could be encrypted, the associated files could not be.
When I released it, from the thousands that enjoyed it, I got requests for help from dozens of people who had big problems with it.
This took up a lot of my time, which I was ok with until I found a common thread to these complaints.
One by one I found out that those having problems had been "exploring" the files in the scenario folder, and had decided to replace one thing with another, thinking they knew what it was for, etc.
So much of my time wasted on people who should have just played the bloody thing, and stopped digging around in the source files.
A similar situation again, where a program I wrote for the Driving Sim community (which allowed replay camera positions to be determined by you) was released as a beta to the community, with all the warnings that go with a beta.
After some people started prodding around in the source files, they found that my program would delete all the camera positions from their track.
They were completely oblivious to the fact that it was their "messing with files they shouldn't go near" that caused all the trouble.
Even when I took the beta private with a dozen or so testers, one of them continued to mess with the files (I guess he was trying to be clever) and kept getting problems.
Of course, I didn't find out about that until I'd wasted many hours trying to track down the problems he was having.
How would the Devs here like it if half the bugs on the tracker for Construct were the cause of someone using unreleased versions of code that no-one else was using?
So, to clarify again, it has nothing to do with not wanting people to see graphics or hear music from the game.
If people want to do this, then that's fine.
It's the same as watching how to complete a game on YouTube or buying a strategy guide for a game before you've even tried playing it!
I don't understand why anyone would do that, but they do, which is fine.
This request is so that I can rename the extension to ALL my exterior files, so that it looks like I'm using some sort of proprietary filetype to hold my game's data, and so deter the casual gamer from bothering to dig through them.