Are you joking or something?
Of course not. I bought Deus Ex to play Deus Ex. I didn't buy it to install Steam. This isn't the first time either that this has happened. I still haven't touched the Orange Box either after i found out that installing Steam was required. Yes, i still haven't played Portal.
Point being is that i feel duped and can now understand the reason why someone would pirate it even if they have a legal copy. Personally, I wouldn't have bought it in the first place if i knew that steam was required. Maybe i just should return the damn thing instead.
//EDIT: No matter, i'll return it for the xbox-version instead.