I will join in here.
The way I see it, it largely depends on the type of work you are doing, and the market you work in, to determine if one of these is worthwhile.
I see the biggest advantage in places with high labor rates, as you are really just replacing added labor with an expensive tool. The cost of the replaced labor determines how long the payoff is on the tool. I could see these showing up on freeway projects and other high profile jobs, especially where there is limited room for additional machines.
Large building sites may be another place where they make some penetration into the market.
For me, I could see several places where I could use one, but not with anywhere near the utilization it would take to spend the money on one new. If there comes a deal on the used market that may do, but my small excavator is a 330 Cat, and they are pricey, especially for the limited use.
I am sure that over time they will come to be accepted, then demanded more and more, but it will take time. Remember it has not been that long ago that quick couplers were a novelty that few wanted to pay for, now it would be hard to market a rental excavator without one.
The other thing I think of is that having a rototilt enables one excavator to do work normally done by other machines. Those other machines may be better, like the example of the grading tractor spreading the topsoil better than the gradall in the video, but by having the rototilt, the one machine can stay busy more often, and the quickest way to improve the return on investment of a machine is to increase its utilization.