It's been my experience that it depends on your point of view...
Not everyone is genetically disposed to be thin. Some folks could starve themselves almost to death and not get that thin - different body types, ya know. Other folks might have the right body type, but are too busy - making a living, raising kids, etc., to be able to maintain that kind of figure. For them, staying that slim takes more leisure time than they have. And a lot of those skinny models pay a big price to stay that thin so they can look good in fashions (e.g. drugs, throwing up...) Most women are not willing to pay that price.
Also, any mother will tell you that childbearing can make some major changes to the body that no amount of diet and exersize will erase. Are they "sloppy" because they don't have the time nor money to get surgery to make themselves "trim"?
Also, any woman of a certain age can tell you that perimenopause and menopause can wreak havoc with your body and metabolism. Many a formerly trim woman has suddenly found the phrase "rude awakening" very apropos.
The greatest swimmer in history (as in she has broken all distance/speed records and has swum in places that most folks couldn't dream of tackling) is Linda Cox. This woman can swim circles around every other person on this planet and she's nowhere near trim - zaftig would be a better description. But, she's incredibly healthy and fit. Being healthy, regardless of your genetic makeup or body type, seems to be most important.
Just my $.02