I don't normally post on the immigration threads because I haven't quite reasoned out my personal position on what should be done about the illegal's who have lived in the US for more than say five years.
I do take exception to your statement about semi-skilled and low-skilled wages not being taken into consideration as having any affect on real wages being depressed. I'm unsure if I'm misunderstanding you. Semi and low-skilled wages help to make up the backbone of real wages. I'm going to use new home construction as an example because illegals are hired for a lot of the low/semi skilled positions in that particular industry.
When I was a young adult I had a number of acquaintances who had summer jobs working on new home sites as carpenters, bricklayers, roofers, painters, etc. Upon graduation they would find construction work on a full time basis and they would command a larger per hour wage because of their summer job 'internship'. As they gained more experience along with more knowledge they would be able to advance up to being able to manage a crew. With even more experience they would strike out on their own and become a contractor. Even working as part of a crew, these men were able to support themselves and a family.
In looking at the kids who graduated with my son (he's 28) I can't name one who went into construction. The illegals took the majority of the jobs and the jobs would no longer support a single young man much less one who wanted to raise a family. By the way, I'm not talking union either since there wasn't a union for construction workers (at least not in Texas there wasn't.)
Based on what I saw with my son's peers, in order to be able to get a job where they were self-supporting, they first had to go to college. A large number of his friends graduated with large debt in the form of student loans. Needless to say if they wanted to have the standard of living of a 'skilled' worker, they had to command a larger salary or they had to live paycheck to paycheck.
I'm not sure what you consider real wages to be. To me a real wage is any wage which will allow a person to be self-supporting and to have some discretionary income.
A real wage is one that keeps pace with inflation and is a wage at which the purchasing power would be comparable to that of another era. The problem with such a measurement, though, is that it does not take into consideration innovate and technological advances that make our lives easier or more enjoyable. The fact that we're are sharing opinions over the Internet even though we could not have done so prior to the 1990s is some kind of evidence that we are better off today than we were in our past...unless of course you despise the Internet and the lethargic culture it has created. But then, being as lethargic as we are, we are now living longer than we ever have. Can you explain these things if our standards of living are not improving? These things cannot be measured just by comparing wages, either.
As for the rest: perhaps our drives, our educational system, our values, our expectations, or any combination of these are a little out of whack and need to be revisited by everyone today. No one said that markets were equitable and no one entitled us to a life of ease without busting our asses to achieve success.