TracGantt isn't forgotten, but it's definitely neglected. I'm thoroughly convinced that putting tickets themselves on a Gantt chart, by using extra fields, was a fundamentally bad idea. The correct thing to do would be to use Milestones, which already have a lot of the implementation details that we were adding to Tickets.
I plan to rewrite TracGantt at some point in the future, but I don't know when that will be.