You know, this is actually a very good question. And I give you credit for making a substantial topic both in terms of the reasoning it's based on, as well as the relevance it has in a way to the bigger picture of society.
The definition of empowerment or progressiveness shouldn't be based on how many times you've shed your clothes or kept them on because that gives a skewed picture of reality, as is evident by the examples you've noted at both ends of the spectrum. Sonakshi in particular is someone who vocalizes her choice not to 'expose' her body, sure...but the reasoning she bases it on is more than a little diluted. If she was comfortable with her body (a la Vidya) or had a smashing one like other actresses, first question is, would she not be without inhibitions and doing what they do too? And secondly, irrespective of the way her body looks, would the reasoning behind her choice ever be 'I want to do self-respecting roles that I feel befit or give due substance to me as a woman, rather than living up to or making my choices under the pressure of my family's honor or the ideal of the perfect Indian woman'...?
I think it's likely that the answer to the first question is yes. If she had what the others have, if she could carry and flaunt it, you best believe she would. But even more than that, let me step back a little here and actually say that what she wears right now or has worn in the past is not exactly the garb of holiness either. She has worn dresses and saares that are 'short' or revealing in their own way, so the argument that 'the length or type of my clothes represent my honor' has not really stood up as valid in her case. Secondly, her reasoning has never been to do self-respecting portrayals of women...what does it matter what length your clothes are when your only purpose is to titillate and be objectified? Again, she uses the wrong yard stick to measure her 'family's honor' or the 'ideal Indian woman' because clothes really are an argument she has failed, and wrongly used to justify what she can't do or doesn't want to do.
Empowerment or progressiveness are about how evolved you are in your opinions and the choices you make...how open-minded you are to different lifestyles, different choices and believing that be it you or other people, all people should be allowed to live and do as they want or are comfortable with. It's about being comfortable with your own sexuality and with your body no matter how it looks, rather than being apologetic, defensive or mindless with its use or portrayal. Empowerment is based on self-respect and far from being about clothes...it's about wanting to contribute to society at large by believing and doing something substantial on the level of ideas and in fact rising above the materiality of clothes.
The closest actress in terms of empowerment or progressiveness in current mainstream Bollywood is probably Kangana, and then Vidya. Kangana's had her share of publicized screw ups (and whatever else may be going on in her personal life), but on the public platform she has shown that she's evolved in thought over time and can hold an opinion of her own even though it may be in contrast to the ideals or norms of the industry or society. She has insecurities but she owns up to them and her mistakes, shortcomings, and choices are presented without justifications or a sense of being apologetic. She states things as a matter of fact and has grown to accept, while being committed to learn and change even further if she finds need. Vidya too went through a phase, learnt from it and now just comes across as someone who has a DGAF attitude. She wears ridiculous clothes, is whatever size, and still remains largely unapologetic about it. People still criticize her for it, but she seems happy being who she is and what she's doing...and that's empowerment, accepting who you are, owning it, and running with it without harking to societal ideals or the pressure of family honor to justify who you are or your choices.
Clearly Sonakshi has not presented herself for the public to believe as such about her, no matter how much propriety or dignity she stands by or does maintain in person. Since her reasoning and actions do not align with what constitutes as empowering or progressive in my book, it's hard to see her as a shining beacon of the cause, no matter how much she may otherwise convey or try to verbalize it.
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