Taxation of dividends
The issue of double taxation goes well beyond dividends. Every dollar of corporate income is taxed twice - once when it is earned by the corporation, and once when it is returned to the shareholders, either in the form of dividends or capital gains. But since the shareholders own the coporation, they are taxed twice. This unfair policy has the effect of restricting capital formation, all else equal.
Either eliminate corporate taxes altogether, or eliminate taxes on dividends or capital gains. I'll admit that there are some wrinkles, but they can be overcome.
Corporate taxes or taxes on dividends and capital gains (one or the other) should be set to the personal income rate. Income is income.
As for the "unintended consequences", so what? Markets should not be distorted by stupid policies. The fact that they get un-distorted should be an intended consequence. But I agree that changes should be phased in. People should not be screwed by changing the rules in the middle of the game, no matter how worthy the goal.
JMHO, and one which I know is not popular here, so I'll be quiet now.