I'm all in favor of closing loopholes and simplification, but almost every single mainstream simplification that has ever been proposed has amounted to nothing more than an attempt to remove progressivity from the tax system. What makes the system complex is not the existence of more than one tax bracket, it's the bewildering array of itemized deductions one can take. Most of the 'simplifications' set out to accomplish two goals it seems: 1) simplify code 2) somehow lower rates. Unfortunately, when they try to be "revenue neutral" by closing loopholes, those hardest hit are the middle and lower class because of the mortgage interest deduction. So ultimately, many of these plans look like a tax cut for the rich and raising taxes for the middle class by taking away their deductions.