I think it is important to keep things in perspective and not get bogged down thinking about things in terms of "what happens when blah blah".Your arguments make a lot of sense from a physics standpoint. Obviously (or maybe not) Jeep's engineers must have asked the same questions and faced the same issues, and come up with a solution that offers some benefit beyond what is already available; if not superior, why bother with the development costs? I'll wait to see the specs before I decide whether it's worth it to our particular family situation.
The Jeep will certainly have an ICE large enough to power the vehicle off road, when the battery is discharged. That is clear.
Jeep understands that while many Jeep owners like to go off road, you do not live off road.
You do not spend 90% of the time off road. For the overwhelmingly fast amount of owners, 90% of the time they are drying to the shops or work and maybe once or twice a month get out for a jont up to the woods for a little adventure.
The PEHV is designed for that 90% of the time.
Like it or not, the never generation of buyers have different priorities than the older folks. Environmental stuff is important to them. This does not mean MPG, but overall emissions.
If they can buy a Jeep, go off roading and still "feel good" about it, who cares? It's not harming you or me.
If you do not like it, lukily there are several alternatives now. Even a diesel!
Regardless... You better get used to it. in 15 years it is pretty unlikely a IEC engine will be offered by any make.
Personally, I am still hoping for fuel cells and electric motors, but who knows.
Something with all that torque off road would be pretty fun though.