Yup, people are insensitive and thoughtless.
My (least) favorite is when one person gives a sweet compliment, and someone else immediately either shoots it down or somehow renders it moot. For example:
Person 1: "You look amazing! You can't even tell you're pregnant from the back!"
Person 2: (eyeballs me like a prized heifer) "Suzy Q. was even smaller than that, and she had the nicest glow..."
Or the "un-compliment" that folks often offer, which sounds like a compliment but is really a put-down. "Oh, look at you! Your ankles and face have hardly swelled at all!"
Eh, what? I'm not swelling, dangit!!!
: Ladies, we are beautiful! To quote a bumper sticker, Mean People Suck.