Income remaining stagnant or going down for bottom quintile is not really a problem. When you look at the economy over decades what truly matters is the quality of life people could afford at that time compared to 20 years back despite being in the same quintile. That is going consistently up thanks to the efficiency brought in by the growth. A focus on redistribution might help the bottom quintile temporarily but it would hurt the efficiency of economy by moving the money from private hands to government hands. This hurts not just the poor people but also the middle class and rich.