Their focus on erotic human beauty might be seen as objectifying the self, but I think it is more likely valuing the self. The movement from awkward Godly ideals to individual human beauty may be indicative of a shift from a somewhat socialized state to the capitalism that bloomed from trade interaction with other cultures. Classical Greek art was commissioned by the State, so had fairly generic themes in comparison to Hellenistic art, which was more varied I believe because citizens who accrued wealth were able to commission what they wanted. Also individual artists became famous — a sign of humanism — and had more leeway to do the projects they wanted.
The nude statues of women could be seen as objectification, but I think it is a sign of women’s rise to political equality with men, and that they no longer needed to be protected as precious possessions (swaddled). The male form was free to be ogled, why not the female? When Alexander the Great was off conquering, his mom Olympias ran the court of Macedonia. Women started going after political positions through their sons and husbands, their legal and economic responsibilities increased, and they were recognized with honors for their work. Where in the Classical period women had citizenship loosely through their husbands, Hellenistic women were granted citizenship for their works. They also gained control over slaves and property, and were responsible for their own debts. Women entered the sports world through horse racing and foot races. They had access to education, and became writers, philosophers, and poets — Errina of Talos, who wrote Distaff is an example: https://www.attalus.org/poetry/erinna.html . There isn’t a lot of art in the Hellenistic Period wing that shows this change, but the body language in the Nike of Samothrace does pretty well — striding forward, strong and feminine.
I don’t believe it was a period of regression — it was a period of gaining personal power through commerce, and the recognition that women could be able to add to society. Countries that offer equal opportunity to women and allow free trade treat their citizens as individuals, and give them the freedom to pursue happiness.