I would be more concerned about social media (or media in general) than a harmless barbie. For me I loved barbies growing up and never once thought about their body shape - they were a doll after all. Similarly Lego man/woman had strange proportions but I never questioned that.
My body issues came from an obsessive mother who commented on weight/size from the age of about 4/5 and a ballet teacher (this was the 80s) who constantly told us all we had to diet if we ever wanted to be successful dancers. This too from the age of 5. No wonder I always thought I was fat (and never ever was even close to overweight).
If I am lucky enough to have a daughter I will totally allow barbies - I think denying them of them could potentially be worse (they will wonder why). I think it's important to install good self image and body confidence by what you do & say and remember you can't shelter them forever. TV and social media will give them a good dose of unrealistic body image and try as you might they'll get exposed to it sooner or later.