It's hard to think of any statement that on its surface sounds less controversial. Eliminating loopholes means more revenue. Everyone likes simplification. Efficiency!
So why doesn't it happen?
This fantastic chart from Credit Suisse's Neal Soss is the answer. It shows the top 20 biggest "Tax Expenditures" which cost the government over $900 billion in the 2012 fiscal year.
So you want to simplify the tax code, what are you going to get rid of?
Are you going to eliminate the incentive to provide employers health insurance? Are you going to get rid of charitable deductions or pension contribution deductions? What about dinging the child credit or mortgage interest? Or how about clipping Social Security benefits for retired workers?
You get the point.
Good luck to the politician that votes to eliminates any of these