That's as opposed to the gifts of the separate tax struture for capital gains taxes
The separate tax structure is a reflection on reality. The exact rate is where the gifting comes in.
You can earn a 4% nominal return saving for retirement, have a real return of $0, but still have to pay taxes under a system treating all forms of income identical to earned income. Hence the reason those who are least likely to earn a return in excess of the inflation hurdle rate currently pay 0% in taxes on capital gains and dividends held long term.
Higher income earners who earn double the rate of inflation are currently taxed at 30% in real terms. I'm guessing those who earn in excess of that are way more likely to pay an inheritance tax. The real gifts are in deduction loopholes. Mentioning charitable deductions and life insurance benefits is more on point IMO (Mitt Romney plan hint hint).
FWIW, raising taxes on dividends & capital gains would be the best way to raise my taxes without hurting the economy one bit. They should go up moderately.