Here's how I see the Quicksilver thing: I don't know if I'll like it, but I understand it. An important part of what makes Wanda interesting is that she starts as part of a brother-sister team and moves beyond that. In the comics, this was achieved by giving her a romance with Vision. But it doesn't look like this film will have time to start that (plus, defining a woman by her relationships with men is not quite as common now as it was in 1970).
I have no doubt that Whedon is more interested in Wanda, because she's a powerful woman and because when he was reading the Avengers in the late '70s, Wanda was much more prominent in the team than Pietro was. It does make sense that he'd want to focus on her growth as a character. And in a movie that's packed with characters and not all that long, it has to be done in the quickest way possible.
I have no doubt that Whedon is more interested in Wanda, because she's a powerful woman and because when he was reading the Avengers in the late '70s, Wanda was much more prominent in the team than Pietro was. It does make sense that he'd want to focus on her growth as a character. And in a movie that's packed with characters and not all that long, it has to be done in the quickest way possible.