I don't think there's anything wrong with buying a Barbie for a one year old. People bought my daughter dolls of all types even before she was born. However, I put them away until she was older.
Barbies have so many tiny pieces that go along with them. Even the brightest 1 year old would likely swallow a shoe, purse, button off a little jacket, or just stick Barbie's hair in her mouth.
They make really awesome "baby" dolls for little ones that don't have any hair or clothes that can be choked on. They look like little newborns. Even my son had one and we still have it. (He's 15). His little t-shirt that was given to him at the hospital when he was born is on it.
Like I said, nothing wrong with buying certain things for your kids, but I think there are age guidelines for a reason when it comes to something like a Barbie doll.
Just my opinion.
Best wishes.