Is it really too much to ask that people who buy the game legally actually own the game, and not the other way around?
Well, LEGALLY, you never owned any game in your life, or any software other than the code you wrote yourself. The thing is Steam offers an unprecedented degree of enforcability of this notion.
And to the OP, out of sheer curiosity, how did you go about installing the game? I'm guessing most people install Steam, activate the game and hit "install" in the Library tab (because selecting that option normally downloads the game, it's not a bug!) instead of running setup from disk. I'm REALLY curious, because I own a fair number of steamworks games and not ONCE did I experience this issue.