I'm not seeing a whole lot of "purpose or benefit" to a hell of a lot of other dances idols do.
But I'll be clear. I think objectification is something the viewer does. I have a hell of a lot of experience with analyzing these things from my religious days. I turn my mind to myself and consider how I view women. Have I objectified them? Do I? When? Why?
Their behavior or dress could only incite something, but I always had the choice, and always do. I can enjoy a beautiful girl in an objectified manner when she's just being cute, conversely I can look at a stripper and think about her life and what she deals with and feels, or I can enjoy a show a girl is putting on with a dance in the frame of a social connection where she is being sexy for the fun of it to express that side of humanity and I receive it as the one she is directing it to in appreciation of her as a person including her physical beauty and her celebration/expression of her sexiness as a fun thing. There can always be one or the other or both things going on, and the mindfulness and respect is always a choice I make that is not made for me by her dress or behavior.
As for empowerment, I see that as an entirely separate dimension to things, and while in some sense connected to objectification from others, it is far more connected to judgement, which is another thing I am familiar with considering as I tried not to judge others. If I see a girl dressed or acting in a certain way, how can I know what it means to her just by seeing? How do I know if it is degrading compliance or fun or boldness to her? I don't. But if I automatically judge the action in itself, I have done her a disservice, both looking down on her and also placing a controlling attitude over her life about what she is allowed to do or wear in order for me to still respect her. Neither is fair if I don't really know what is going on with her.
I do understand the perspective you are coming from. There are actions that a woman can do that are much more-likely and perhaps even intended to gain a response of objectification from men, and in one sense if you are seen as an object rather than a person that is socially disempowering in some ways. However, if kept entirely there by those rules, that makes women's freedom of expression subject to men's minds, especially if you start judging them for crossing a certain threshold, which is something utterly nebulous and up to the personal responsibility and individual limits of each man. Judgement like that is the foundation of purity culture which is attributive to suppression of women's freedoms, a component of rape culture.
Is it complicated? In one sense yes. Because on the one hand you leave them to such personal freedoms of sexual expression while withholding judgement, yet on the other hand you know there is a definite connection between the actions and the objectification that is the other side of the same coin (minimization of their person) that you're trying to restrain, so you don't want to hold a double standard between what you expect of yourself and what you expect as a standard from them. But therein is the major catch, which in another sense makes it very simple. We aren't talking about a standard of behavior to result in appropriateness, we are discussing freedoms for them on one side and mental self control for us on the other. So both the judgement and the objectification are under the control and responsibility of the men, no connection to women's freedoms except when we use their decision to use their freedoms to excuse ourselves from our responsibilities.
So the answer, in my view, is to stop judging women for what we do or what we think. It is unjust to women to do that, and also degrading of fellow men to consider them as helpless to properly direct their minds to appreciate sexuality as well as the personhood of the women who wield it. These sort of acts from women may be immature in that they play off those old instincts and patriarchal social dynamics, so I think it is okay to consider them immature in that view, but I can't put "shameful" in there without feeling as guilty as if I were objectifying them like the men I would use to justify that accusation. Is it inherently risky on their part since it is a play on instincts which come to all without social training? Yes. But socialization to control our instincts is something we have done with many things, and I think we can do it with sexuality if we openly allow and face these things and try rather than stuff it away. Taking that risk in freedom, to me, is a step made from someone already empowered, choosing their own life and risks regardless of what people think.