It doesn't surprise me that she failed to win an OG. She was never head and shoulders above her field, particularly technically, and she lost a couple of other competitions to Lipinski. She was very consistent and that reflected in her career (a couple of her WC titles were tantalizingly close). Had great presentation, but it's sooo overrated, cause so many people act like she was the only one with any artistic flair (or even the most), which I don't think she was. She knew how to "connect" to the audience hence her popularity (even though it doesn't mean much to me), and that is a nice quality, but is far from being the end-of-it-all of artistry. But people will feign over emo performances with "passion".
As for Yu-Na, I it's really mostly bitter Kwan fans who are deriding her. If you're concerned about the quality of skating, she should be your least of your worries, because she's probably the only one in her field with any flair (only Miari is close to her), especially in comparison to her "rival", Asada, who's pretty much a jumping/spinning/spiraling machine.
I don't think she's up there with Kwan artistically, but she certainly has her qualities, particularly her ability to connect with the music, her very soft edges and some of the best-looking jumps; and at least she's performing very well constructed programs. Is she getting overhyped? Yeah, she is. Especially that her spins and spirals need a lot of work.