Fa_jing - one could argue that paying taxes or voting is good, paying taxes does go to social programs, better highways etc... and voting, if done with a good concious could be argued as "good" as well. however I will say that they are two different categories. Taxes are necessary for a nation to survive, maybe not so high, but still.
Ultimately I think it's a product of two things, the human habit of categorizing, two of the biggest categories that strike an emotion in someone are good and bad. Also, being that there is not much seperation of church and state, and definitely wast in the past.

Here is my take on morality. Morality is subjective but necessary to have a civilization, which is also subjective. A society of war and "murder" could be viewed as "good" by those within the society. Logans Run was a good example, the idea that retirement at the age of thirty was a good thing and helped society to survive by not straining its resources. Later they find that it isn't necessary any longer because the world can now support human beings in large numbers and so death at the age of thirty becomes something not necessary and since a human beings biggest imperative is generally to survive, will probably become and "evil" idea in the future of that particular reality.