[Gormo]

> This is the opposite of idealism - is there a word for it?

Far from being the opposite of idealism, this approach is in fact the only one by which high ideals can be approximated in reality.

> You seem to be complaining that something is impossible because it can't be implemented in a perfect utopian way.

Quite to the contrary, the complaint is not merely that the pursuit of these goals would fall short of perfection, but rather that the consequences would largely be the inverse of the intentions.

In essence, idealism is its own opposite -- if you're looking for a single word to describe this critique, some good options might be "correctness", "efficacy", and "reasonableness".