Well, wasn't Pokémon more of a guy-related game, though? For a while until Crystal, they only had a boy being a Trainer, then decided to add a female character. And some Pokémon are more male dominated, but I don't really think that counts.
As far as I know, it's more likely for a male to be a scientist/professor than a female. But they may have a girl professor one of these days. Even if it HAS to be Professor Ivy.
But like Pandeji, it's tradition. What if the main character's father was around instead of the mother? Personally, I would find that weird.
Maybe that's just me.