If a real woman with boobs above an A cup wore this dress, her nipple would jump out with the slightest wrong move. I know Barbie is a plastic doll with completely unrealistic proportions; her cup size is one that most real women achieve through surgery. I'm no Puritan, and I think the Disney Princess franchise is far more detrimental to young girls than Barbie's wardrobe. But, here's the thing about big boobs, doll or human: you don't have to do much to emphasize them. It's as simple as avoiding turtle necks and baggy clothes, finding V neck T shirts and wearing a bra that fits well. Barbie's boobs would've looked just as supple in a white dress with a neckline that only showed a bit of cleavage. This dress is something you'd wear to a night club with bottle service, not to take your dog to smell other dogs at a park. (Unless you're the kind of terrible person who would buy a dog just to pick up dudes).
And speaking of nipple slips, a Chinese company put this bra on the market.
Why yes, those are slots so your nipples can be out on display. (Presuming your nipples are perfectly in the middle of your boobs). Maybe it's just me, but I like to choose who sees my nipples. And once again, the people who want to look at boobs will do it even if they can't see your nipples.
And then there's the clevaage caddy...