Are we too mean?

Sometimes I feel like society encourages us to be mean to each other. What I mean is that I see more and more friends (and even family) that like to tease each other, often to a point that is kind of crossing the line. It really is bullying, except that everyone has a good laugh, including the person that happens to be the butt of the joke that day. But that person is basically expected to take it in stride, or risk being seen as not being able to take a joke. I see it particularly in people younger than me, for example: I’ve seen my youngest sister just flat out tell her friends that she doesn’t want to talk to them today. Which would seem harmless enough if there was a reason for it, but really it’s just to be blunt and kind of mean.
Also, sarcasm is glorified. Now, I can appreciate sarcasm… it’s funny. I know this. But I feel almost like some people aren’t able to have a straightforward conversation anymore because they have become so used to resorting to sarcasm. The whole thing is kind of ugly, in my opinion.
We are just generally unfriendly sometimes. I know that I’ve gotten more than one odd look if I happen to smile or say hello to a stranger walking past. It’s as though people have become skeptical of random kindness.
I’m not sure if this phenomenon applies to countries outside of the USA… but have we taken it too far? Or is it just my imagination? When does it stop being funny and playful and begin to be just wrong?