Here's my experience: My parents were extremely affectionate, we were all nursed past a year, never scheduled, co-slept, natural childbirth, etc. and they HATE Spock.
Their beef is that he was very much in favor of child-led actions, that your kid chooses to do certain things (instead of your responsibility being to make sure that he does certain things). My parents firmly believe that he ushered in the new spectacularly selfish "ME" generation (beginning in the 70s) that has been taught that their own satisfaction, their own pleasure, is the best and only goal.
This is in huge contrast to the parents of that generation, who had gone through the Depression and WWII and had been taught that the greatest good was to sacrifice yourself for your family and for others. In the 40s and 50s, it was taken for granted that you'd keep even extremely infirm parents until they died. My mom, for example, grew up (in the 50s) in a four-bedroom single-family home with her parents, her four siblings, and BOTH sets of grandparents. Her own father had been accepted to MIT right before the Depression, but when his parents' money disappeared had given up his educational dreams and instead married at 19 and devoted his life to caring for his family. He became a traveling salesman for a paint company, so was away for days and weeks at a time. One grandfather was extremely senile and needed constant care, a grandmother was crippled by arthritis, another grandfather was relatively hale but still needed normal daily care. NOBODY complained--it was considered a mark of shame to put your parents "in a home" as long as you could eke out enough money to put corn and beans on the table for everyone.
So a Spock baby would supposedly think that he or she should not have to be made uncomfortable by moving back home to take care of an elderly parent, to give up a career, to move states, etc.
(Note that my own opinions are not reflected here; just reporting what I understand to be the case.)