Yes, the web OS definitely needs a simple, easy-to-use file manager.
I've been trying to copy a screenshot taken on my LG Smart TV to a USB drive, so that I could upload it. Unfortunately, the only way I've found to do this is by opening the file in the LG Photo Edit program, and then saving it to the drive - and this is less than optimal since the screenshot comes across as a small clip on a black screen.
The Smart Share application apparently doesn't allow you to share files from the TV onto a USB (or any other) drive. That's not very smart.