I made a Lego 6 Plus to test this very kind of thing. Result: I still want the Plus!
Maximum stress in my front pocket comes when crouching down--like tying my shoes--but the device seems to have enough wiggle room in MY jeans even then. Regular sitting? Hard for me to imagine that pose straining a phone, unless maybe it gets yanked out hard and bent by hand. I have plenty of room when sitting, and my pants are neither super tight or super baggy.
(Plus, wouldn't FRONT-pocket bending force go the short way, around your leg cylinder, not the long way? The long way, your leg is like a splint preventing a bend, right? Whose thigh bulges out in a knob right there?)
I would think, then, the risky activities would be crouching (maybe), OR carrying something heavy that presses on your front pocket. Or sitting On it--in or out of pocket--if you're heavy enough or for long enough time. Pay attention to what puts forces on your new device.
I bet the bend seen came from one single incident that the person may or may not remember. If they do remember, they'd rather deny it and get a swap.
What's the rate of this? Anecdotal? How many of the people really DO know that they did something unreasonable? People who have had no issue rarely bother posting. Are people who have a true mystery-bend a significant percentage of the masses sold? (Not saying either way--but it should be asked.)
I also would wonder about a factory defect maybe--maybe a few devices arrive bent already? Old PowerBook G4 screens often used to have a slight curve.
And it doesn't make me wish it were thicker/tighter in the pocket AND made of plastic, like some other brands!