One problem I see with these studies is that people who run them get to define the terminology (i.e. what is "political", what is "informed", what is "art", what is "important") and their subsequent measurements. Naturally, they define these things by their own standards, values and behaviors. This is not a problem specific to blogging, as anyone who has taken Women's Studies 101 can easily explain.
Another problem might be that the "surveyers" don't know the first thing about conducting market research and aren't getting an accurate measurement of what's really going on. I think the methodology used in the recent Blogads survey bears this out.
However, there is some good news (sorta) for women bloggers. What will eventually drive "professional" blogging is revenue, specifically advertising revenue. Most of the ads you see on the A-list sites are related to the upcoming elections. After November, that's all going away.
Big, mainstream advertisers target women, Latinos, and young people. They aren't interested in reaching middle-age white guys who sit around in their pajamas all day writing and reading blogs as these guys don't consume at the rate of other market segments. The big advertisers haven't found blogs yet, but they will if industry growth continues. Well, the A-list bloggers, by and large, don't reach these market segments (BTW: Why isn't anyone asking where the bloggers of color are?)
Given that, instead of criticizing the behavior of women, people of color, etc. on the web, people with aspirations for making a living at blogging might ask what they are doing wrong as they aren't attracting these audiences. I know one thing: You don't do this by claiming that they are "uninformed."
You can also find this post here.