The other side of the coin is that a lot of the Li-Ion alternatives to CR123 primaries are protected cells. As such, they have a tendency to just shut off when the cell discharges to that point. Whereas a CR123 will continue to output something until it dies the true death. In cases where one is depending on their light for what could be a life or death situation, I would lean toward using primaries, or more likely, have a light using primaries as my backup, with my main light using Li-Ion. That way I have the economy of using rechargeable cells most of the time, but if I do use a light to the point of shut-off, I will have a second light that I know will work, and not stop dead on me. I think that is why most of the boys currently playing in the sandbox are probably still using primary cells with their lights. I for one would not like to be kicking in doors and clearing a building and have my light suddenly stop on me. That would not be the best time to be changing out cells.
And don't start on the protected/unprotected on me. I think most people would agree that there are still a lot more protected cells out there than there are unprotected. Yes, as more and more users get familiar with rechargeables, and with the increase in low cost high quality smart chargers, the demand for CR123s will diminish. But I don't think it will ever go away. I mean, one can still rather easily find 'B' cells for sale, and the biggest use for them was in tube radios 75 years ago.