Any idiot can give a pat answer of diversification under all conditions and at all costs,

If you live in a particular state, and you want to minimize risk, why would you want to buy bonds of another state, just because they have a higher yield?

Given that risk and reward go hand in hand, wouldn't that by definition increase your risk since you may not be as knowledgeable about another state and you may not be as able to determine whether conditions have ocurred which negatively affect the value of your investment?