That would be true, but for one, the percentage of women with nipple piercings is statistically insignificant. For two, you don’t actually have any measurable way of telling with certainty how popular those piercings are. So it’s not really as comparable to hair color, which you can ascertain at a glance. And even then, I would expect some kind of clarification that this has been obtrusive or obstructive to the speaker. “I’ve been disappointed so many times to find out that my date had their nipples pierced” or something to that effect. Just saying “some women are doing this aesthetic thing to their bodies, and it disappoints me” is not really saying the same thing.

There may be a fundamental disagreement here over whether or not it is valid to feel a sense of ownership over other people’s appearances. “Oh no, that guy would’ve been so cute if he hadn’t grown out a mullet I wish he hadn’t” would be a strange thing to think, let alone verbalize, about a stranger. It implies that by virtue of that man changing some aspect of appearance the speaker has lost something tangible. It might give the speaker pause in that situation to realize that their language kinda makes it seem like they’re entitled to “mullet-less” men. We also have to consider the emphasis that puts on men who do have mullets. The speaker in this case is collectively denigrating all of them for failing to meet their expectation of non-mullet hairstyles, despite those men not knowing the speaker and having nothing to do with them.