The issue has little to do with an upper, middle and lower class existing and mostly to do with the widening gap between the rich and working class/poor and the middle class disappearing. It's natural for society to function to have a class disparity of some sort or we end up in a communist state, which has been proven impractical in the past. As I mentioned in this following post, it's largely about the widening gap between the rich and poor due to rising inflation and salaries not keeping up:
http://www.the16types.info/vbulletin...=1#post1315234
Basically, the rich are becoming richer and the poor are becoming poorer because if you do the math, it's pretty clear that salaries are not keeping up with inflation and that has been an on going issue since the 1950s. You can increase minimum wage to help deal with it, but it's just a band-aid solution for the real issue at hand, which is salaries are not keeping up to inflation. Our quality of life has decreased quite visibly and noticeably compared to the 1990s and it's obvious to see why. It's also a trend that has shown no means of slowing down and it is continuing at a steady pace.
In an ample amount of North American cities, renting or purchasing a home is not affordable because of the ludicrously high house prices, then add in the rising cost of bills, food and most items and it's not difficult to see that our quality of life decreasing. That is the main crux of the issue in the end, if our quality of life had remained stable or improved then this wouldn't be an issue, but it's a serious issue and we can't just brush it under the carpet that the poor and working class are envious of the rich when the gap between them is widening and there are numerous statistics that prove this is happening.