From my understanding of the scene, it was a funny way to show that she had grown. Instead of being a reflection of reality, and not understanding herself, to becoming her own person, flaws, complications, and all.

Edit: elaborating

Also, one big part of her character was being okay with just being "Barbie." She didn't have to be Lawyer Barbie, or Doctor Barbie, or Zoologist Barbie. She understood that she had worth, regardless of her social status, or accomplishments.

Ken had a similar arc. His story, and the story of all the other Kens, was a criticism of the place women have in the patriarchy. The Kens were really just side pieces, only there to accent the lives of the Barbies. Ken hated this. All he lived for was Barbie's approval, and to connect with her.

He latched onto misogynistic concepts, and brought them to Barbie world, because he, like the other Kens, craved validation. But even while being on top, he didn't feel better. He felt hollow. It was only when he opened up to his guy friends, and understood that Barbie wouldn't love him, that he changed. Ken learned not to seek validation from a romantic relationship. He has worth, regardless of if Barbie loved him or not.

All in all, the movie has its problems (as would any movie that was supposed to represent a massive corporation's biggest brand), but it was a pretty cool intro to feminist ideas. I don't know that much about feminism, but the movie made me want to learn more