For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
It is perhaps a bit hasty to assume, as your final paragraph seems to indicate, that only women have these vanity issues. i'm just sayin...
I actually think the answer is addressed very well and it is not discriminatory at all.
Some surgeries are more common for women but others like laser hair removal or dental implants are common even in men. The list would be longer then the available writing characters, this is the issue.
As it would have been unacceptable for a man in that day to have "adorned" himself, 1 Peter 3:4 speaks primarily to the women of that era who had gotten caught up in following trends to show off their finery when they came to church.
Now days, both men & women can get caught up the same way. Not always with "fine apparel" or "wearing gold" as modern times have provided many other ways, including plastic surgery to make an outward show leaving the "hidden person of the heart" overcome by pride & vanity.
M. Henry suggests, the "outward adorning of the body is very often sensual & excessive; for instance, when it is immoderate" & "when you are proud & puffed up with it."
The idea that plastic surgery can make a woman prettier or a man more handsome is a sad notion & it goes against the LORD's call for us to walk in humility.
And humility is not gender specific!
Col 3:12, "put on tender mercies, kindness, humility";
Titus 3:2, "showing all humility to all men";
1 Peter 5:5, "be clothed with humility, for "GOD resists the proud, but gives grace to the humble" (Prov 3:34)"
Humility is not dressing down, that would be "false" humility (Col 2:23) like some groups who insist on drab colorless clothes that fit like gunny sacks. True humility comes from being IN Christ, being who you are IN Christ.
And as we stand fast IN Christ, in total subjection to Him, we can know what humility truly is.