While it is somewhat arbitrary, I am sure that "Barbie" is intentional, the somewhat obnoxious repetition of the word "Barbie" fits the theme. Also, maybe you stopped reading a little too early as the case where the title is a character name is specially addressed.

"It" may be the the special case here, as it is a very common word by itself but that a movie is named like this is notable enough for it to be included.