What's the marketing gimmick?
Unlike, say, gendered kinder eggs, where blue is marketed towards boys, and pink to girls - these are not. You get what you're given - a surprise. Which means boys/men eating pink chocolate and girls/women eating blue.
And non-binaries sitting in a corner sulking, not getting any chocolate.
As I mentioned upthread, funds from sales go to Plunket, NZ's biggest children's charity.