First, it doesn't make the file hidden, it just grays out the icon. To make it disappear under this scenario I would have to enable "hide system files", which introduces other problems. (Show system files and show file extensons are the first things I change in ant Windows installation). Second, I have to do this to every one of my files - there's no global ability. I know I can select a bunch of files and change the properties on all of them, but what about those files with the same extension on other folders or drives? That's more work than it's worth.