I don't know what DQ's attendance numbers were, but it always seemed crowded when we were there. Even when one of the counter service restaurants closed, the Genie was turned off, and some attractions were shuttered, it was still full. We went to DQ every trip, nearly every year from 2001 - 2017. We used it as a Water Parks & More option ... even in June, 2017. I grew up in arcades and my boys (now 22, 20, and 18) always had video games at home, but we loved going to DQ.
DQ didn't fail. Disney's marketing team failed.
Had DQ been priced and marketed as the largest arcade at Disney (and not as a step below a theme park), it could have survived without upgraded games. Why? Because the games were fun. Pac Man, Defender, Galaga ... fun. Air Hockey, Guitar Hero, Fruit Ninja ... fun. Pirates of the Caribbean: Battle for Buccaneer Gold ... incredibly fun.
Wreck-It-Ralph 2 is out in a year. If only Disney had a large arcade it could use as a tie-in to the movie ...