Here we go again. This is a moot discussion, there are not enough American citizens out there to fill the positions, period.
And as far as wages go the DOL is pretty strict on what needs to be paid.
Also its more expensive for the company, since it has to pay for immigration fees.
Yeah, it can be used as a tool to keep people from switching employers, since they always require sponsorship.
But this is like the old slogan all politicians use "Bring manufacturing jobs back to America", never going to happen.
So wake up, get your kids into science and engineering and they may still have a job. Or better still save up for them, since they are going to be hanging out in your basement playing WOW.