If you look at primitive societies, women typically do not cover up. No one bats and eye. Why? Breasts aren't sexualized, they are normalized. You're expexted to have breasts as a woman, they're expected to be of various shapes and sizes, favor is not given to "prettier" pairs of tits, and it's expected that they will change somewhat over the course of your life.
Free the nipple is meant, I think, to renormalize the female breast in western society, in much the same way that mothers nursing in public is meant to normalize the female breast. There was also a calendar a while back of post menopausal women posing topless. That's two that come to mind, there's plenty of others, I'm sure.
Those actually worked toward normalization because in order to reclaim the female body for ourselves, we have to subvert the shame that's meant as a societal behavioral control, right?
Shame was never applied to young women's breasts, but to old women's breasts and nursing mother's breasts. "How dare you flounce your breast around as though it's meant for something other than male sexual gratification" was the idea behind the shaming.
So Florence Pugh's act was never designed to subvert shame in the same way because she's already attractive (young, she fits the maiden archetype), we've already seen her nude in a commercialized sense (on film), and the venue for the act was of pomp and display (a red carpet event).
So it didn't work, and it landed all wrong for what it was claimed to be.
Now, you put Judy Dench in that dress, or every Black and brown actress who have traditionally been denied awards like the Oscars, or a bunch of young women showing up in clearly deglamorized and natural looking outfits, and you do it for a season, not a one time event... now you've got something subversive.
Why? Because it's clearly political, it's a bolder statement, it subverts shame around the female breast, it demands both conversation and response rather than just causing controversy for attention. It challenges notions and laws. It's clearly NOT about men looking at you with lust.
Bit long winded, but that's my thoughts on it. And you did ask. Lol.