1. Trade happens only when both people see the trade as making them better off. Americans value what the Chinese sell. The Chinese sell Americans what they value.
2. Restrictions on trade harm both trading parties (because some of those mutually beneficial trades don't occur, usually in the name of someone who can't/won't trade because they are unwilling to provide terms another party deems valuable.
To be blunt: if you can't compete in the eyes of the people who you want to buy your goods, you should be doing something else.
3. Restrictions on trade are a good thing only if you can convince yourself you know more about the value of what is or might be traded than those who are deciding to trade in #1.
4. If you are a business able to go international, you're always going to go with what produces X most cheaply. Labor is cheaper in China on a per unit basis.
5. Why are labor costs so high here relative to in other countries like China? When average income in China is one eighth that in the United States, you can't operate a lot of businesses and pay your workers $25/hour. Or, for that matter, the American minimum wage: If the minimum wage is $7.65/hour and the person works 2000 hours/year, that totals to $15,300. Average Chinese income is about half that, even after the amazing growth of the last decade or so. Even if you got rid of the collectively bargained extra gains (confusing everyone, including themselves often, the economist calls these "rents"), which outside of the usual suspects like the autoworkers and a few others, is actually a lot smaller effect than people think, and even if you got rid of the costs of regulatory compliance, which are actually a lot bigger than people think, you would still see Chinese workers paid a lot less than Americans.
6. As for the "but the reason the Chinese can sell so cheap is because the Chinese government restricts American companies, protects Chinese ventures, gives subsidies, yadda yadda yadda"? Sorry, that doesn't change #1 and #3. Moreover, that argument, like all mercantilist arguments, simply looks at one side of each trade, namely the value received or not received by sellers. It ignores the fact that the buyers also benefit from all those subsidized trades. If there is no American import tax on French brandy, and French brandy makers continue to get subsidies from their idiot government, then *I* benefit by getting French brandy cheaper....and so I get to buy more of it than I otherwise would.
Regardless of how many restrictions on trade already exist, regardless of where or by whom they are imposed, adding another restriction can only do one thing: reduce the total number of trades.
Restrictions on trade work one way and one way only, by shifting wealth from one person (the evil competitor in foreign lands) to another (the noble suffering American producer/worker). And since each of us tends to see themselves in the latter role rather than the former role, such restrictions remain ever popular. Unfortuately that shifting, that redistribution from the "shouldn't haves" to the "should haves" has another, and unavoidable effect: the wealth that could be created from the gains from those trades that don't occur never gets created. And so the total pie to be divvied up is smaller than it would otherwise be.
The Declaration of Independence only talks about the "pursuit of happiness." It doesn't promise, nor can it fulfill a promise, either of a particular level of individual happiness or of a particular share of the total happiness. Only God, coercive action by the state, or voluntary trade between buyer and seller can do that. And restraints on trade can only determine the share of the happiness pie; they can't increase its size.
And do not be conformed to this world, but be transformed by the renewing of your mind, that you may prove what is that good and acceptable and perfect will of God.
Romans 12:2 (NKJV)