That's the question the AJC asks in this article, which points to a belief that downtown Atlanta lacks an "after-hours component." An excerpt:
While nightlife downtown is not as pervasive as it was in Buckhead during the area’s heyday, it is not nonexistent. Several clubs operate at Underground Atlanta, and the Tabernacle brings throngs of concertgoers to the area on a regular basis. A handful of restaurants also has become popular at night.
Still, much of the city’s inner core is deserted after the business day is done, adding to the perception that downtown is dangerous. In addition, metro Atlanta has more than one urban center, which gives investors in nightlife many options beyond downtown.
I probably go to Atlanta about once every three months. But rather than nightlife, it's usually shopping or restaurants that bring me there.
I've been to a couple clubs in Atlanta, and it's not a bad scene, but the hassle of steep cover charges, overpriced drinks and driving back to town at 3 a.m. can be a bit much.
Columbus-area readers: Is the Atlanta club scene worth the drive?