[clairity]

> ...you would have to accurately model the response of individuals...

but macro and micro are two separate disciplines within economics because of the belief that large scale economic activity can be modeled without modeling the individual agent. it's more akin to newtonian physics where the model breaks down at small scales.

but i agree with your main point about why it's hard to model -- basically humans are wiley creatures who defy predictability, and observation itself creates a feedback loop that changes the model =)