People are naturally judgemental, humans as a whole need a solid ground to find to create the illusion of safety, all though in the back of our mind we know anything can happen at any time if we think we have a control over the world around us we are safe. I say do not think of others opinions they can only effect you if you allow them to bother you. Everyone is entitled to their opinions but only your opinions truly matter to you.
Because its human nature to judge others. Natural instinct. You can't get looking at someone and getting an impression whether good or bad. It would be nice though if people saved their judgements till later.
judging people in my opinion is a rude thing that everyone does. I know a girl and she was overweight and I just thought she pigged out and stuff but turns out she had a cancer that made her fat when she ate healthy and stuff.