Sadly it follows on the heels of a plethora of previous ideas which have been ineffective at best and destructive at worst. These children also achieved less than the generations before them because they were taught to think highly of themselves rather than to strive to please others. As a reaction to this idea, the pendulum then swung to the concept of tough love , where children were left to bear the consequences of their childish folly unaided by those in authority over them. They were then abandoned to their own devices in order that they may learn from hard experience. Unconditional love is a reaction to that idea.
Unconditional love is really a contradiction in terms, an impossibility.
It purports to love someone without making any demands on that person, setting no conditions for them to receive love. It seeks to define love in human terms, confusing it with being nice . It is perfectly reasonable for parents to show approval when their children please them and just as proper to show disapproval when their children displease them. To deny that would be to deny participating in a relationship. If we never expect a response from our children, we indulge them to their peril.