@the_beheld via @marginalutility asks Should We Praise Little Girls For Being Pretty? @nourishthesoul replies "It's wonderful to remind each other that we are all beautiful, but maybe we have it wrong?" Why I get tired of “You are beautiful!”
What's the purpose of commenting on a person's looks? There are three possible positive motivations - to make the person feel good, to make oneself feel good, or as an attempted building block in a relationship with the person (or her parents). There are also three possible negative motivations - to trivialize or attack the person, to put oneself down in comparison, or to trivialize or block an attempted relationship.
If you want a little girl to feel proud and important, then there are probably better ways of doing it than commenting on her looks. As the_beheld comments, "being praised for something you can’t help can feel hollow or even confusing". (The same applies to telling people how clever they are.)
Telling grown women that they are pretty, or that their daughters are pretty, may be an effective chat-up line on some occasions, but the line often carries a slightly bitter aftertaste, as if there is some buried hostility towards self or other. Some women and girls may become accustomed to hearing how pretty they are, possibly starting with their fathers, but that doesn't necessarily mean they believe it.
Perhaps the Sex Pistols had the right idea when their lyrics progressed from "pretty" to "pretty vacant".