It’s all about quality.

Mr. Magazine points to foreign examples, but perhaps more importantly for the North American market, he refers to the approach being taken by Hearst.  This passage is key:

“David Carey, president of Hearst Magazines, explained to me in a recent interview why Hearst is upsizing its magazines: “We are investing in a number of our editions because we do want to be best in class in all of our titles. We do know that as far as advertising, we want to be, ideally, one, two, maybe three; in terms of a category, you don’t want to be four or five.” In the last three years, Hearst has upsized Country Living and Good Housekeeping, and published both Food Network and HGTV magazines in a larger size than the majority of the magazines in the marketplace.”