It is a contributing factor to a convoluted system that makes it harder for Americans to get jobs and harms our economy. When a corporation can get an employee for a lower cost, they will do so. What is not taken into account is the costs that went into training that employee. These are skilled positions that we are talking about, so the employee would have needed college education. Now look at the cost of an education in the United States. Graduates here cannot afford to take a job for the same low pay as someone that had a government subsidized education, as exists in many other countries.
Another factor is the flow of money. People coming here for these jobs are not immigrants. The money that they make is largely flowing out of the country. It is hit by income tax, but once it flows out of the country it is gone. Money earned by a citizen is generally put back into the economy which benefits other business sectors. This is something that our representatives should consider. We don't have a one-world taxation system, therefore, we cannot have a truly level one-world employment system.
I could go on with more examples, but the underlying problem isn't the individuals coming here for the jobs, but the long tail effect that they have on the economy.