Which is understandable, Fran is the only one of the main cast with anything unique about her appearance. She's got immediately recognisable bunny ears, as well as heels and recognisable (Read: Revealing) clothing. The others are regular people in, more or less, regular clothing. There's nothing that really stands out about them at first glance.
Cloud had his giant sword and spikey hair that made him stand out, Squall had his, at the time, unique weapon and scar, even Zidane had his tail. Even Tidus had a visually colourful design, despite a lack of other distinguishing features. 12 had, err... Vaan and his washboard abs? I mean, I'm sure they were probably intended as eye candy, but they're not really enough to make him stand out. There are plenty of other musclebound guys in video games, but very few bunny girls.
Outside of that, Fran suffers from the same problem as Kimahri does. They've got a very unique appearance, but little else going for them. Talking a little bit funny isn't a substitute for personality. The only real element of their backstories we learn is that they both left their homes to live with Humans. It's why I'm a little disapointed both of them made it into FF14 - I would have prefered something native to FF14 rather than imported from other games.
Balthier on the other hand is charming, a master of witty repartee and all wrapped up in a Han Solo package. He embodies about what 3/5ths of the internet wish they were, in other words. He's got more broad character appeal rather than just pure sex appeal. It's why I figure he'll be along at some point in the story, FF14 hasn't ever really had a character like him.