The Brooks study Kristof references in his article has similar conclusions as Peter Schweizer's excellent book, Makers and Takers. Schweizer contends that left-wing, pro-welfare state public policy leads to an infantilized citizenry that is self-centered and hedonistic rather than productive and conscientious about personal responsibility to others. Schweizer presents survey data that shows that liberals generally expect other people or the government to take care of people in need (even a family member), rather than believing that they have some responsibility to help.
Schweizer implies that because liberals have less self-control and are more conceited, they project these attributes on to others, and so they advocate policy that is designed to restrain the base instincts that are most prominent in themselves.
I think this may be true in general, but I do know some liberals who have a very strong sense of personal responsibility, and are highly productive and conscientious, but they assume everyone else is a selfish child who needs the firm hand of the state to keep them from hurting themselves or others at every turn.
Either way, it is a type of misanthropy that I find abhorrent. Rather than inspire people to become better, it seems to inspire them to become worse.
I cannot argue with a single point in your post; and I concur with yours in re "but they [liberals] assume everyone else is a selfish child" and Mrs. Schweizer' "liberals have less self-control and are more conceited, they project these attributes on to others".
Merry Christmas, Oblomov!