Even though excessive amounts of irritation are definitely unpleasant and counterproductive, irritation in itself can be a useful alarm bell. I've noticed that, through some kind of fast heuristic, my brains turns irritation on very fast when I'm hearing or reading something that contradicts my beliefs. This often happens before I've consciously fully evaluated the statement, and triggers further analysis. It's actually a very precious instrument, and I'm more worried when it doesn't trigger at all.