Why does it bother you sir?
Flags are a symbol of the beliefs of a nation. Burning a flag is saying that the beliefs of said nation are of no consequence.
Edit for clarification:
This may not be true of every country in the world. However, when I see an American flag, I think of the virtues of said country and those that died to see it's independence. Furthermore, when I see the Irish tricolour, I think of those that died to secure independence, and the idea behind the countries ideas of a united Irish nation. Therefore the burning of either of those flags I would see as a travesty to those who fought and died, and those that currently inhabit the country represented by the flag.