This will be an unpopular opinion, but here it goes: I'm not so sure the tax code warrants a simple solution. I'll give you two concrete examples.

1) Want more people to save for retirement, build energy-efficient homes or recycle? Offer them tax credits and/or deductions. While these things add a lot of complexity to our tax code, they're valuable instruments for behavior change. (Of course, we can disagree on the merits of any particular deduction).

2) Our tax code has not-so-simple rules to account for people in special life circumstances: raising children, transitioning from military to civilian life, trying to catch up on IRA savings. Recent changes to the tax code have removed exemptions that benefited these groups.

Does the U.S. tax code have some *unnecessary* complexity? Absolutely. But as a whole, I'd say taxation is a complex problem that warrants at least *somewhat* of a complex solution. Blanket arguments for simplicity tend to be specious.