It may indeed be true that Wyden is exaggerating, and even a very smart tax reform will leave some number less than all Americans completing their taxes in under an hour, but that number could still be quite a bit larger than it currently is, which makes it a goal worth striving towards. And lord knows we're not near the upper end of easy tax payments. Not only is the structure itself overly complicated, but it's been two decades since the last significant clean-up of the tax code. The accumulated loopholes and detritus are long overdue for examination.
Additionally, tax simplification is the sort of policy which would make a great many people very happy at just about no extra cost to the government. Which makes it all the more important to do. Most of the great gains in policy are to be made addressing the needs of the worst off. But most of the votes come from the massive middle. For these folks, the country actually works fairly well, if not perfectly. To institute policy that will substantially improve their existences through material transfers is, given their size, prohibitively expensive and politically difficult. But policy can improve their lives in other ways.
To simplify their dealings with government and make their lives at tax time 2008 simpler than they were during tax time 2007 is both (conceptually) easy and substantively worthwhile. And it can be a good that increases middle class support for a policy that also includes more serious reforms that aid the poor, like simplification and unification of the forms that govern benefits (see Max Sawicky's proposal here), getting the IRS to do the taxes of 50 million Americans themselves (see Edwards' proposal here), or taxing work income at the same rate as wealth income (see Wyden's proposals here). Simplification can work in service of progressive reform.
And finally, the perception of a complex tax code is bad for liberals. The more folks look at the loopholes and exemptions and deductions and forms and judge -- correctly! -- that the system can be gamed by those with the money and time to cheat, the more they'll feel like suckers for paying their fair share, and the more receptive they'll be to tax cuts and the dulcet tones of Grover Norquist. A system that obviously treated everyone the same would leave fewer fols feeling like dunces for cooperating with it.
