Well, it's all subjective, and as I say, we're probably never going to agree on Sasha the way we do on other skaters. (Like Mirai :agree
But since you brought up ballet, I will make this point.
Athletic ability is as important in ballet as it is in figure skating. You can emote all you want and you can be as flexible as you want. But if you can't do fouettes en pointe, you will never be a professional ballerina.
But here's the real magic of ballet: professional ballerinas are SO good that they make what they're doing look easy. That's the magic Sasha had when she was on, such as in the 2006 SP. That's the magic that a skater like Flatt has not at all.
Being "artistic" and having "good presence" is not why this woman can do this:
http://www.youtube.com/watch?v=vC1mBBscVHg&feature=related
The artistry here comes from the fact that she does it so well, she makes it look easy, like she's not straining at all. Just like Sasha at her best.
My point is that it takes great athletic ability to look graceful when you're doing something as physically straining as a fouette turn, or a triple flip, or a back charlotte spiral. You can't really separate artistry and athleticism in a sport like figure skating. They are linked.