You are a novice user if you deleted the /usr directory. You obviously have no idea of how Mac OS X works otherwise you wouldn't have done this in the first place. On top of that, you blame Apple for allowing the folder which is hidden by default for being allowed to be exposed, you've obviously never used Terminal.app or you would know that it isn't hidden, just hidden from Finder. If anyone besides yourself is to blame here it's the poorly designed (and free, you do get what you pay for) dynamic DNS software you used which exposed the /usr folder in the first place, but in reality, the fault lies completely with you. NEVER ASSUME ANYTHING, not only in life, work, etc. but especially in computing.
Nuff said.
And They Said the Mac Was Intuitive