Steam is completely integrated with the game. The server browser in-game is actually just steam, so it really would make no sense at all to have TF2 without steam.

What exactly is your critique of Steam, just that you are fundamentally opposed to DRM? I do agree that it's something that I don't really want automatically starting up with my computer (even though I'm a pretty heavy gamer, I don't use the steam friend chat or anything) but as a platform and a piece of software it doesn't seem too trashy.