I don't understand your comments at all. The phone is metal, so I guess I didn't think it needed any added rigidity at all. But I don't usually sit on my phone. The Speck case seems plenty rigid to me as well, although I did not try flexing it without the phone in it.
Also, the Speck adds shock-absorption material all around, including on the back. The Spigen Hybrid only has it around the circumference. (Or maybe even just the corners? They call it "Air Cushion Technology." I love it.) Phones don't only land on corners when dropped, though, and gravity does not care. It's easier to make it thin when you're not adding any shock absorption. I could paint my 6P and call that an ultra-thin "case." The Spigen Hybrid does look nice, though.
There are the videos of bending the phone. While the video was sensationalized, the phone does have a "weak point" between the power and volume buttons, much the same way the iPhone 6 does. If you look, a lot of the metal is "missing", replaced by the buttons. And while the phone is metal, it is aluminum -- not the hardest/most durable of the metals -- and there are people here who have had minor issues with the phone bending.
In my case, I'm not worried about having heavy duty drop protection, I rarely drop my phone and, when I do, it is typically a relatively short drop. Additionally, drop tests show the phone holds up pretty well. Instead, I tend to carry my phone in my front pocket. While I'm being careful with it and typically pulling it out of my pocket while sitting, there are times I have to bend or do other things while the phone is in my pocket. So, in my case, I'm more worried about bend protection than drop protection.
Oh, and even with a drop, it is largely only if it falls directly on the back (where the plastic piece is) that the Spigen Hybrid doesn't really have any shock absorption. Especially with the "camera hump", the phone just isn't going to land where the hard plastic is located, rather than TPU, on the back. The other areas are all covered with about the same amount of TPU as the Speck case, just without the hard plastic coating, including around the back glass. And, my point about rigidity, having the hard plastic go almost to the camera bump, it does provide extra rigidity at the weak point in the phone.