Why you call those seams? I still don't get it.
Shock absorbers: I don't think so. The screen itself always has a rubber seal/weatherstrip to maintain the glass avoiding contact with the surrounds.
The glass on the iPhone screen is tempered, right? so it will shatter by design when the internal tension is released.
The ones with the theory that they are bumpers, why as they are in different locations?
Sensors, why? It has the multitouch screen, gestures will do the expose.
There is something else we don't know about those.