The female character thing is really a tip of the iceberg. There isn't much point in expecting male directors, producers, and writers to do female characters as often or as well as they do male characters. There doesn't seem to be a huge push of women into the production side of the business; a slow trickle if anything. If anything, women are better represented in front of the camera than behind it.
As to Buffy, I always thought the namesake character was the weak link of the show, and the supporting characters and some of the more innovative writing was what made it work. It seems to me that if anything Hollywood learned the wrong lesson from this show, which was that martial prowess is important. Now we see tons of frequently waiflike women beating up on much larger men (sometimes with supernatural powers for justification, sometimes not), an image that could be seen as cool and subversive when Buffy did it, but is now badly overdone. What we don't see is more reality-based images of violence against women, because it would be too upsetting for the mass audience. We also don't see any really interesting and well-developed female leads who do things other than gratuitous violence, which again I suspect is due to the people writing them.
I thought BSG tackled gender issues much better (despite an almost exclusively male creative team behind the scenes), and every significant female actor on that show has had a lot of success since then.