Whether it's a work of visual art with private parts exposed, lyrics of a pop song, or a passing comment of another person, some people love to take offense. They spout off in righteous indignation at the lack of standards or lack of good breeding demonstrated in another person's actions. During the 2008 political campaign taking offense was an oft-used influencing tactic, as though US voters would interpret thin-skinned reactions to satire and the usual political mud-slinging as strength.
Sometimes giving offense is an intentional act to get other people riled up. The point of the words, picture, or action is to garner attention, even if the attention is negative. When people sit up and take notice, even if it's to react in anger, at least they are engaged. So perhaps in some instances the intentionally offensive behavior could be interpreted as a cheap shot at being noticed. Or perhaps the individual is attempting to make social commentary by testing or stretching the boundaries of their audience's values. It may be provocation, but without the intention of injury.
Probably more often, (unless you're a character in a daytime drama) offending is not intentional. The words or actions are intended to be innocuous, but the receiver is negatively stimulated when the message hits their hot (habits of thought) buttons.
It's a choice to feel offended. This is not to be confused with being wrong if you have hurt feelings. But taking offense is a manner of interpreting the actions of other people as threatening or ill-intentioned. Sometimes the offended one thinks (incorrectly) that they and their sensibilities are being targeted. Some of the collateral damage associated with the process of taking offense results from the offended party's response to the triggering event. They may extend or magnify the impact of the incident by taking retaliatory action - complaining, gossiping or counter-attacking. In this manner one action, interpreted as an offense, can grow into a war.
Effective behavior regarding offense
Often the most effective manner of dealing with offense (if you want to keep feathers unruffled and the water smooth) is to avoid giving it, and to avoid taking it. You are only in control of your own thoughts and your own actions. You can choose to behave in a way that is designed to be helpful, not hurtful. You can challenge ideas without injuring the other party, and when you perceive that something has gone wrong you can approach the person directly to address the misunderstanding.
Perhaps it could be said that it's self-centered to take offense. You may be assuming incorrectly that the other's actions are directed at you, with intent to upset you. It's probably not about you. Instead, try to understand the message, and if you're not sure what was meant, ask. Offenses given and taken create walls in relationships that are preventable.