Let me say from the start that this is a post in reaction to quoted tweets that I saw, and I hope I've got the story right.
What apparently has happened is that Jennifer Lawrence was not paid as much as her male co-stars for a particular movie, in which she had a comparable role.
While this is a lamentable state of affairs, just WHAT is lamentable about it may depend upon your point of view.
Most, if not all, screen actors are members of the Screen Actors' Guild (SAG), which has a set scale of wages for actors in films. This is just one of the constraints under which films are made, and few object to it. If Jennifer Lawrence was paid less than SAG "scale," I think she'd have a leg to stand on.
But she says herself that she didn't push for more money - as did her male co-stars - because she wanted to come across as more friendly and likable, or words to that effect. And that's her option. (Obviously, she WAS paid more than scale - just not as much as her better-negotiating co-stars.)
But the modern-day mantra of "freedom of choice" of one's actions always seems to neglect that any choice comes with consequences; in this case, not as much money. If she didn't negotiate as well as her male co-stars, one can hardly chalk that up to sexism on anyone's part. Failure of her agent? Possibly. Misplaced desire to be "liked," as though Hollywood isn't oriented toward the bottom line? Absolutely.
So, the lamentable part here is that Ms. Lawrence either is unwilling to take off the "Please Like Me" sign during negotiations, or does not have an agent who will negotiate as aggressively for her as her co-stars' agents negotiate for them.
Ms. Lawrence has tremendous ability and deserves the title "star." Being a shrewd, tough negotiator - or hiring one - in the long term will only help that status, not hurt it.