Perhaps I should let you in on a secret: I don't really believe children should be neglected. That use of the term was ironic. What I believe is that we, as a culture, have redefined the healthy autonomy of children as "neglect" in order to justify our belief that they need parental attention all the time, for reasons that have little to do with children's real needs and a lot to do with us. My guess is that this is because we haven't grown up ourselves. Emotionally, in some important way, we're still children, and this causes us to think of our children as peers. Ironically, this means we're actually failing to fulfill the parental role for them even as we make parenting the central meaning of our lives.
By the way, all these ideas come from my own struggle to understand what it means to be a good parent, something I by no means claim to have mastered. I do believe that to do it well, it is vital to distinguish one's own fantasies about parenting (which are always self-centered) from the real requirements of the job.