^ your enemies? please - no nation, even if your president was a wuss, would dare to attack. They would have the entire west against them - and for all Europe's soft diplomatic ideals, if it's total war, we have the industry and know-how to beat your enemies to a pulp with you.
Most likely because the parties think that this is what the people wants.. If bashing your opponent gets votes, then it's gonna be taken to an extreme - kinda like the free market. It won't stop until the market is saturated. It's the same over here - reality TV and game shows have made TV and politics more about show than substance.