
If it bothers you, it’s worth talking about. Nipples are halfway between normal skin and genitals imo, regardless of the gender. I feel it’s a valid complaint, maybe just nipple covers/patches is a compromise. Especially if you buy them for her or give her the money for them, but be prepared for a “no.”
I mean if she doesn’t care about being seen like that I guess you shouldn’t either. You can point it out but if she shrugs it off that means she comfortable with it. It’s her body and what she wears is an indication of what she wants people to see. Now if the clothes are making you uncomfortable you’ll have to figure out why and if you should care more than she does.