Why do people get offended so easily?

maybe they have an open heart?

They do? Somehow I don't think you're telling the whole story. Do you mean they "get offended out of the blue?" or after someone says something like "I think you dress horribly"? If it's the latter, which it probably is, who WOULDN'T be offended at that?

Low Self-Esteem.

I dont know, cause I dont get offended easily.

Words have meanings, and indicate intent. If you didn't have that intent, why did you use those words? Should I not care what you think or feel? Then why should we have any relationship at all?

I would also say low self esteem.