I think there's a global issue where the majority of "strong female characters" are being written by men, to be honest, and in most cases in shows designed to attract a mainly male audience. A lot of times I feel like companies are struggling to write believable female characters, but seem to never consider, y'know, just hiring a woman. I think the main issue is we need more women allowed to have creative control over characters of their gender.
Well, I mean, K-on was directed by a woman, adapted by a female screenwriter, had character designs by a female character designer, had a lot of women working on the storyboarding, animation, etc. So good news, some studios are doing exactly what you're asking for.