We see a lot less of Arthur as the story goes on, and so there's more opportunity for him to have become less of a bumbler and more of an advocate.

Maybe it wasn't Fleur specifically, but I seem too recall a certain amount of looking down on veela. Maybe it had to do with the Quidditch World Cup in GoF, but I'm pretty sure that we were exposed to negative attitudes towards veela before the Beauxbatons champions and Fleur arrived, and there was still plenty of suspicion or something else about veela afterward.

Harry is the muscle. He casts the strong spells and is the broom flier (although Ron is the keeper, and that suggests some very good broom skills of his own.) and it, once you point him at something, Harry's going to try and beat it in the most direct way he can. Give Ron enough confidence and resources, and he can probably draw up an excellent plan, which Hermione can field-marshal (and Fred and George can run intelligence and sabotage with).

Although now I am contemplating the story where Ron is the thinker, Hermione is willing to go along with it, and they both take charge of getting Harry to have a normal life, as much as one can, rather than playing up the Boy Who Lived angle.