>>53673254Can't be certain, but saying the anime influenced it might be putting the cart before the horse.
I think it was recognized right away that Misty was the most prominent girl character in the games that was around the same age as the protagonist, and also the first named girl he meets. This is likely why she was chosen as the first female lead of the anime to begin with. So when it comes to practically any variant of Red, Misty has eternal first girl status, for whatever that's worth.