Don't apologise for digging it up, it's a really good comment! Barbie being an accessory to other people's growth is a brilliant way of framing it that I hadn't considered - I love that!

I also like framing it that, at the beginning of the film, everyone's identity is somewhat defined by Barbie (as a concept - not the character):

• Barbie is obvious - she is just living the "dream" Barbie life and doesn't know anything outside of that. She struggles when she starts to gain humanity because she feels inferior to the other, more accomplished Barbies (doctor Barbie, president Barbie, astronaut Barbie, etc);
• Ken - his entire life revolves around being "and Ken"; He exists to be Barbie's mild love interest, and is basically irrelevant when Barbie's not around;
• The mother is basically clinging onto childhood optimism and better times by playing with Barbie. She's using Barbie as an escape, but she's also warping the concept of Barbie with her depression;
• The daughter is wholly and actively rejecting Barbie (and her and her friends are also references to Bratz - the "anti-Barbie"), to the point where she's overly cynical, tough, bitter, and not empathetic enough.

By the end of the film, I think everyone ends up empowering and being empowered by the ideals of Barbie (the concept) while also rejecting the relationship they had with the concept at the start of the film:

• Barbie learns to be human. She gains empathy. She sees the value in women having roles like doctor, president, astronaut, etc, but realises it shouldn't be an expectation for every woman and that she's not inferior for not having one of those jobs;
• Ken starts his journey of discovering his own identity, rather than just being an extension of/accessory to Barbie;
• The mother and daughter repair their relationship and the mother (we can assume) stops her "depressed Barbie" creations as her life improves.
• The daughter realises some parts of Barbie's message are positives - that it's meant for empowerment rather than to set unrealistic expectations. So in some ways, she embraces the concept of Barbie, which is a rejection of her previous relationship with the concept.