Why are people obsessed with curves so much?

I mean yeah they’re sexy and womanly. Men prefer curvy women for wives but why go crazy on it. I admit as a girl I envied curvier girls because they had bodies most girls die for. I was stick thin. I’m slim with curves but not thick. I like my slim body.
I’m not saying it’s wrong to prefer curves. They’re sexy as hell but don’t shame girls and woman that don’t have them.