The only people who want extremely complicated tax codes that we have are the wealthy (they can afford tax consultants that know the loopholes), CPA's being an expert in this justifies their high salaries, and the IRS (again the code requires quite a few extra jobs)
Sales tax is simple, would all but eliminate CPA's and IRS and the loopholes that the Billionaires use.
It is stupid to tax corporations which is why there are "tax havens". What you want are corporations to be successful, to be profitable, and to employ a lot of people. It is stupid to have complicated income tax rules. Property tax makes sense and sales tax makes sense.
You can discourage people from buying luxury items or hummers, or some other item that is deemed harmful by simply putting a higher sales tax on it. Billionaires who don't want to pay tax on multimillion dollar yachts and mansions can instead invest the money which in turn creates jobs and helps the economy.
Sales tax is simple to administer and is transparent to the people. If you want to buy a Mercedes and they are charging 50 or 60% tax on the car the people will be wondering why the government is spending so much money. It is a naturally regulating system where those who are generally the best educated and tuned into politics would see the biggest cost from big government.
Our current tax code is upside down where Warren Buffet pays less in tax than his secretary.