That's always been the story, Titan cards have always been more baby compute than monster gamer hence sacrificing gaming performance for compute performance, Nvidia were actually quite shocked the original card sold as well as it did (outsold the GTX690) and so many gamers bought them.
Well it was a good bit faster than most other cards at the time so its no surprise to me it sold well and id be surprised if it was a shock to NVidia. You don't call a card "GeForce" and not expect it to sell to gamers if its faster than the other options for gamers.