It would help, but it's not a panacea. The onerous regulatory burdens placed on manufacturing create costs not incurred in foreign assembly plants. Taxes are applied to profits, not revenue. The problem is, to make something in the US at a price point that is competitive in the market place, it is (sometimes) even difficult to to turn a profit, let alone worry about the taxes on that profit.
Back to the iPhone example that seems to be popular on this thread, most electronic components aren't made in the US for two primary reason. One is labor, and the other is hazardous waste disposal. There are dozens, sometimes hundreds of hazardous waste materials generated as a bi-product of making those components. In America, that increases costs dramatically. In China, it doesn't. That goes straight to the bottom line, and it's not a little number.
Yes, our tax structure hurts us, but we have regulated our way out of the manufacturing business as well.
Certainly regulation is part of the problem, no doubt.
But it isn’t just the tax burden. It’s the costs of compliance. It’s the burden placed on capital, which is one of the most important ingredients in any business enterprise.
Regulatory reform is structural repair. Eliminating the income tax and everything that goes with it would be a refurbishing and reinforcing of the foundations of our national prosperity.