Good luck on tax reform
The current tax code, with its many, many targeted items, is the most powerful weapon in the politician's arsenal. It allows the politician to punish political enemies and reward political allies, and it does it better than almost anything else.
Non-targeted tax concepts like universal sales taxes, flat taxes, "fair taxes," or anything else that works simply and without judgment are poison to the politician. Same for across-the-board tax cuts or increases.
Without the targeting, there is no power to be had.