If you're talking about the popularity of Isabelle/Isabella in recent years in the U.S., I could see it being a factor.
Isabelle first enters the SSA list in 1991 after not being in the top 1000 for almost 40 years (as an aside - my mother, born during this hiatus period, still thinks of
Isabelle as a very dated/"old lady" name!) That was the same year that Disney's "Beauty and the Beast" came out, featuring main character
Belle as "Beauty".
So I think the popularity of the Disney movie, and the connection of
Belle = Beauty in people's minds, could have led to
Isabelle becoming popular.