I've noticed this since they've been casting more and more female leads. They're never written like actual women. I ain't gonna lie, this Charlie character was a pretty hot male fantasy. Cute girl, into classic cars, total gear head, loves awesome 80s music, has a lame job that puts in her adorable outfits, has just enough issues to make her sexy without being a problem. I think it works for this movie, being a transformers movie. This movie certainly wouldn't have worked if she was a girly girl, but they probably could have pulled off the ugly duckling outcast who gets the transformation in the end. Eh, pick your cliche I guess.
I rolled my eyes at the name Charlie.
She did have a lot of vulnerability which did offset it.
Well, I went to school with a girl named Charlie 30 years ago so I didn't actually find that strange at all.