The reason that economists adjust nominal data to "real" numbers is that they are trying to create a better picture of general welfare after adjusting for inflation. If an economy produces $100 worth of widgets one year and $150 worth of widgets the next, the dollar increase doesn't tell you much if the price of a widget also rose from $100 to $150. In that case the economy has still produced one widget in the year, so welfare has not changed and theoretically real GDP should be flat.
At a fundamental level, "real" economic numbers are an attempt to measure output against time. In the previous example, the data was adjusted to have a more clear picture of the number of widgets produced per year. For humanity, time is really the only scarce resource there is. Therefore, the number of hours worked that it takes a person to buy an item is the true measure of welfare.
Today's employment report showed that average hourly earnings fell slightly to $23.58. Below are charts of the number of hours that it has taken to purchase a home, a barrel of oil, an ounce of gold and "an S&P 500," at the prevailing hourly wage of the era. In general a downward slope would mean that societal welfare is increasing because it would take fewer hours to buy the same good.