Only because we made the "overstaying" an illegal offense. But there's no reason to -- if the guy was paying taxes the whole time, and never committed a serious crime, then we should be happy to welcome such guys, ramping up our GDP.
Don't forget that the paperwork costs a lot, if one has children, can get close to $10k.
Look at Spain -- instead of deporting "illegals", they just made them "legals" (those without a criminal record). Easy, problem solved.