I have come to realize that the tax code is how our government communicates with the citizens. We live in a free society in which our politicians can not arbitrarily tell us what to do and how to make money. However, it is completely understandable that the government would want to try enticing us to do what they want us to do, which is achieved through lowering tax burden on income resulting from those activities in which they want us to participate. This is what makes it feasible to lower your tax liabilities legally, by simply following the instructions inside the tax code itself.
As such, the reality that investment income is taxed at a much lower level than earned income tells me that our politicians would like to incentivize people to become investors. Through the tax code they effectively communicate the message – if you earn money as an investor, you will be able to keep more of it. I say – O.K.