Pretty sure this one will flop other than sales from those who have no other choice for an immediate need. It seems to be a throwback to Honda's old hybrid strategy that also had no real value proposition.
The old IMA was a mild hybrid without clutches to disengage the motor. This is a full hybrid. It sounds a lot like the system in the F150 hybrid. It is also similar to the parallel hybrids Hyundai and others have, including Honda. Hyundai system replaces the torque converter with the motor. I wonder why Toyota and Ford keep it? Is it there heavy loads and trailers?
Sure the Tundra hybrid torque converter (multiplier) and ten speed auto are needed for loads and towing. 22 mpg instead of 19. But why add hybrid complexity for three mpg? Lots of power. To me it would make better sense to put a modern 2.5L hybrid system in a lightened Tacoma to gain real mpg while still having small truck with normal loads and towing.
As stated in the video, that setup is limited in towing/pulling power (work). If the battery pack has a very low SOC and there's a heavy load on the vehicle at the same time (worst case: loaded, uphill, highway speeds), the ICE would really need to scream in terms of RPM to deliver the necessary power. Customers don't like that. At all. The answer to most other questions of "why" is CAFE standards.
There is nothing wrong with the idea of a motor between the engine and transmission, in high powered applications which this pickup appears to be its a better system than the standard mg1 and 2 as it does not scale well with power. The problem as I see it is implementation. That battery is too small. There probably should be a mg2 on the front axle to provide a justification for the weight. I don't know why toyota ended the r&d with ford as they seem to have done a similar system to them, but ford has a slightly better implementation. Porsche tried it both ways and decided keeping the torque converter gave a better driving experience while not really affecting fuel economy. The higher the power of the application the more the torque converter helps, and the lock up can be quite fast. It does add weight and complexity, but in a pick up truck or high powered suv it is likely worth it.
Every power-split hybrid to come out to date has had a worse tow rating than the equivalent ICE model. The Toyota FWD hybrid SUVs had the same tow rating as the Prius; zero. Maybe that wasn't the case with the multistage hybrid system in the LS/LC. That likely was higher cost than a parallel system without any additional efficiency gain. A driveable, and thus sellable, full hybrid system was easier to do as a power-split than a parallel. Took more effort to get the smooth shifting between the the engine, motor, and transmission.
Looks like the electric pick up will have to suffice before manufacturers ever get hybrid versions dialed in. .