Because the economy still hasn't recovered from it.

Take a look at these charts showing total employment during and after the last four recessions. The recessions are represented by gray areas.

First, the recession that began in 1981, which was about as long as the most recent downturn:

1990:

2001:

And finally, the recession that started at the end of 2007:

In all but the most recent recession, four years after it ended the job market was expanding again. Even in the early 1980s, a long and profound recession, employment recovered within 12 months.Today, four years after the end of the Great Recession, the job market is still playing catch-up. That's why we're still talking about it.