Too skinny?

I met a woman over the weekend who said something I consider interesting. Her husband had gastric bypass a handful of years ago. She said he's since gained about 40 pounds or so. I nodded, letting her know that's a common occurrence for veteran post-ops. Her response gave me pause for a moment.
"I think most people get too skinny after WLS," she said. "Your body has to put on an extra 20 to 40 pounds just to look normal."
I said nothing.
Then she added, "Then again, maybe it's just that the rest of us are used to seeing our loved ones be so big that we have trouble adjusting to their new size."
Hmmm...that was profound.
I get told I'm too thin all the time now. My favorite is when people inform me that it's time for me to stop losing weight -- as if I'm blind to my own size. I always let people know that I could lose another 20 pounds and still be within a normal weight range for my height, but I'm also clear that I'm happy at my present size. Though anything is better than carrying 335 pounds on a 5-foot, 3-inch frame, 138 pounds seems to be my body's preferred weight.
I don't understand why people feel obligated to tell me their opinion of my size. I assume it's because in our society, it's considered appropriate to tell someone when they are too skinny in your eyes even though you'd get a dirty look or backhanded if you pointed out an obese friend should lose a few pounds. I'm guessing that woman I met over the weekend has a clearer view into the average person's psyche than I do. If what she says is true, it's a matter of comfort. We know obesity is unhealthy but we're not comfortable with those close to us changing their appearance too much.
I wonder if this phenomenon will change down the line. Maybe in three years, people will be so accustomed to my size that they don't think twice about it. Then again, maybe well-meaning acquaintances and relatives will continue adding their two cents.