Actually the file system is less user friendly than apps.
Sure, a lot of people on this forum are used to it. But for a usual person, app is actually way more convenient. Photos are in the Photos app. Word files are in the Word app.
Same as with email. We don't search for emails in finder, we use dedicated email clients.
"Eventually, file system management is just going to be an app for pros. And consumers aren't going to need to use it".
Here's Steve Jobs on this:
So an iPad is actually moving in the right direction.