Such a claim couldn't be further from the truth. Even on a Tuesday night, several places were popping. I went to PM Lounge in the basement of the Joule for a party. At 9pm, it was already full. People were lounging on the patio of Charlie Palmer. A few student-aged kids were walking around taking pictures and surveying the scene.
I left PM to go to a friend's informal birthday party at Ten Sports Lounge. By the time I left a few hours later, it was full. I walked past City Tavern, and it was 3/4 full inside the bar the patio was full. People were hanging out on the sidewalk chatting in front of the tavern. Again, this is on a Tuesday night.
Other than the French Quarter and Midtown Manhattan, there aren't many places that are teeming with people 24/7. But Dallas has made great strides, and to claim that it's the same downtown from five years ago is not looking at the big picture. Take a walk with me in my new hood, and I'll tell you all about it.