There's also the obverse of the coin, which is where does the victim mentality come from that takes offense so readily?
When did so many people become so thin-skinned? When did they decide that it's desirable to be offended by what is often, in the very grand scheme of things, something inconsequential?

And what are these "slights?" Viennabelle brings up an excellent point: was the perceived slight intentional, and for that matter did it actually occur?
On the internet, especially on social networking venues such as LiveJournal, I've noticed that the omission of "squee"-ing seems to be a capital offense. If that one person isn't overwhelmed with awe, admiration and envy and saying so, why...! And a lot of indignation and outrage ensues.