First of all, EVERY income strata in the nation has had significant real income increases over the last 30 years,. Fifty years. "The Poor" today enjoy amenities that would have been consider luxuries fifty years ago. If you have twice as much as yesterday how can you be "getting poorer"? Would you be any better off if your neighbor's wealth was growing slower -- or faster? The economy is not a zero sum game. Your neighbor's gain is not your loss.
Second, income classes are not groups of people. They are constantly changing snapshots. Very few people who are in the bottom quintile of income will be there ten years from now. Income mobility (in the US) is very high. See http://www.house.gov/jec/middle/mobility/fig-2.gif
Income differentials are highest during periods of expansion and decrease during periods of low economic growth/contraction. If you're really after less inequality in incomes, you're likely to be quite pleased by the slow growth policies that our Congress and President are putting in place. Another quick recession would help even more.
The reason that the highly skilled earn a higher ratio to the average worker is quite simply supply and demand. Demand for jobs that require high levels of brainpower and education has increased geometrically while the supply has increased only arithmetically. Why would you expect any other outcome? Prices always rise for things that are in short supply. It is how the market adjusts. If you artificially put a lid on those incomes, you will simply have an even greater shortage of skilled labor.
All those people who live paycheck to paycheck and don't save anything? That's a choice they make. I absolutely guarantee you that 95?f them could alter their behavior to save $5 per day. $5/day for 40 years would give you $250,000 in retirement savings (@ 5?nnual return).