Well, not everyone is working from the same template.
For those who are large framed, it's nice to see what someone can do with that frame and still look ok. As someone with a large frame, it is somewhat frustrating to constantly see people who have much narrower shoulder and hip bones... it is just, i cannot ever make my bones narrower.
(I'm very athletic so she is not much of an example to me, I tend to find MMA fighters and crossfit athletes with average-to-wide-frames at very low bodyfats to be a better inspiration for me personally. Even though they are NOT MY IDEAL at all and I do wish I had less muscle and was a skinnier type naturally..., they are similar to me, but a little leaner-- achievable!)
I think someone with Katy Perry's body type is the type of body that the Fat Acceptance movement would embrace, if they had any goddamn sense. Because she is large framed, it would probably NEVER be heatlhy for her to be at a BMI of even 18! But she is still "attractive" and an achievable size. And not unattainable at all. I hate when fat-acceptance shit showcases TRULY OBESE people, as healthy/happy/normal.