Much of the point of promoting more manufacturing jobs in the USA is that they pay far more (often multiples) than the current legal minimum wage. The bottom line is the opportunity for workers to earn more, usually much more, than they otherwise would. How is that not a Good Thing?
The positive to Foxconn, if they follow through on both building this plant and paying an average wage of $54k per year, is that it may force other domestic manufacturers (certainly in the midwest near Foxconn's campus) to re-think their typical strategy of off-shoring, moving production to Mexico or suppressing wages in order to maximize profit. Because if they continue to do these things, employees will actually have options to go elsewhere. Of course, it could also force some companies to move entirely out of the country in order to compete - which is in part why we are at where we are right now.
The question you have to ask is will companies be ok with less shareholder profit if they have to pay more in employee wages, or will consumers be willing to pay more for end-product to help justify higher wages for manufacturing? Or both?
Something will have to give in the scenario of bringing on more mid-to-high wage manufacturing jobs. You can't pay people more money if you're not selling your product for a higher price or taking less profit on each sale. In the case of Foxconn, I think their answer has been that they can produce more product per employee, effectively lowering their operations costs, allowing for both higher wages and lower prices for their products.