What is it about the modernization of the world that has caused truth to suddenly become compatible with lies?
It has nothing to do with the modern world... It's always been true that such absolutism is bad psychology. It's the justification for almost all the horrors of human civilization from the excesses of the Inquisition to the Russian Purges. It's true that someone who supports your enemy can't logically support you, but it's a big step to say that anyone who doesn't support you MUST logically be an enemy. Their reasons could be nefarious or honestly prudent, reasonable or unreasonable, but you can't act on an inference without full knowledge. So the "with us, or against us" statement was mindless demagoguery, because it assumes a treacherous motive through the arbitrary exclusion of other possibilities.
I'll illustrate: in retrospect, the actions of certain members of the UN security council seem to have been nefarious, tho not all the evidence is in, it's a more then fair charge at this point. However, any future obstinacy among allies could have as much to do with the perception (false tho it is) that the US government lied, or at least exaggerated the casus belli against Saddam's regime. In such a case, can we claim absolutely that they are just trying to help our enemies? They maybe doing that, but that isn't absolutely their motive. Perhaps you don't agree with it, but it's a fair argument I think.
You make my argument for me. President Bush's statement didn't translate as, "Those who are not with us are ideologically aligned with our enemies." It translated as, "Those who are not with us are helping our enemies."
At some point you care. When push comes to shove you can't afford to.
I will agree with you on one point, the rhetoric does not serve unless lives are believed to be on the line.
Shalom.