In essence you are right. The more the body deforms, the less forces and deceleration acts on the occupants. But you cant allow it to deform a lot, otherwise the intruding part is going to come into the occupant cell and kill the occupant itself. So the idea is to create a nearly perfect and delicate balance between them.
Against that backdrop, what you saw was wrt to the glass not being shattered. I mean, it did in the video. But it apparently wouldnt in the real time.
The reason why this is a good thing is because of something we call ejection mitigation. When a car hits another car from the side, inertial force renders the head/neck portion temporarily immobile and as there is more and more intrusion, they accelerate and hit the glass. Now, in most cases, the glass is already shattered by then. But in the cybertruck, the glass isnt made entirely of glass but a sandwich of multiple layers of resin/plastic/glass. So it shouldnt technically break upon impact.
But regulations call for glass to be broken from the inside because of fire and stuff. So, they will have to make it such that it breaks. In the concept- reveal, I think he specifically said it was just a prototype. I am sure that by the time it hits the road, it will have a different profile.
Same with the body style. The prototype isnt the final design. To make it road legal, there are various safety related tests that the car has to pass. One such thing is a pedestrian protection. The sharp edges in the front side will be replaced with 2 or 3 levels of bumpers. When there is a final reveal, it will be different.
