Politics should be a touchy subject for people. For it to be touchy means the person believes in something strongly. We need people like that in our society so they will fight for what they believe in and promote change when needed. If everyone agreed on politics nothing would ever get done.
Politics is a controversial topic that should not always be discussed because it is a touchy subject. Everyone has their own political standpoints and beliefs and its unnecessary to discuss it because people will become sensitive and annoyed and sometimes debates can escalade into further fights and arguments within friends.
People don't like talking about sports, politics and religion because most people feel defensive about it. They feel so strongly about it that they can't even entertain the thought that they're wrong. So instead of trying to understand each other and find common ground, we dig in our heels and either ignore the problem or insist we're right. Nothing is gained if there is no communication. Ideas should be tough out and shared. Let others judge you and your ideas fairly as they should yours.