There are the manufacturing cost of titanium as well. The material is expensive in the first place, and then machining it is hard on machines and its tooling. You go through a lot of tooling, and the work on Ti is slow and tedious.
Also, the technology of LEDs is moving at a tremendous pace. Flashlights are so much brighter than they used to be. And what goes with being brighter is greater heat build up. Titanium doesn't dissipate heat as well as aluminum. That can result to damage to the light engine (LE).