Mind you, this all goes out the window if a good , if austere life is guaranteed somehow, then capitalism and consolidation away.
1. Nothing, assuming of course they are living those lives. There is a body of evidence, however, so overwhelming that at the lower incomes the people are not leading healthy lives. That is a matter of debate for someone with a medical degree and you could probably write books about this topic alone. Poor conditions reinforce poor behaviors.
2. Perhaps. Of course everyone will argue that their "greater context" is the right one. The question you're really asking here is "are we okay with letting the least productive members of our society suffer and struggle for survival?" Maybe for some people the answer will be yes. There's no logical argument I can provide for those people that will sway them.
3. That is the mantra of trickle down economics that has been proven consistently false over the last 30 years. Neither wealth nor income have trickled down despite increases in productivity. Of course one could also subscribe to the idea of "this is not a problem", but that's the intellectual equivalent of sticking your head in the sand or throwing a tantrum.
To be a bit of a devil's advocate here: Why is that a problem as well?
Assuming that despite their wages "shrinking", they are still leading decent, normal lives then what about that is bad? Perhaps their labour in the greater context isn't worth all that much to others and that doesn't fit in to our world-view? Or are we simply expecting that their "status" or "wealth" should be increasing along with the economy?