What continues to remain thick are the people at Apple that believe most people want thin and fragile while sacrificing battery life.
Exactly, I don't know anyone, quite literally, who wants or wanted a thinner iPhone.
Even the 3G actually felt a lot better in the hand, no-one complained about the thickness.
Better ergonomics and bigger battery can be achieved without making the phone massive, just a couple of mm thicker. Round it off more at the back, even use plastics for durability (again the 3G was never perceived as low quality, the fact you couldn't get a 5C in black also makes me cynical that Apple know what their customers want but push to the higher priced options rather than give it to them).
The fact Apple placed the power button on the new iPhones opposite the volume controls so it's too easy and natural to accidentally squeeze both at the same time seems to indicate that ergonomic testing is limited, making the phone so thin the camera sits proud is also a failure of design - they can quote 6.9mm "thin" all they like but it conveniently disregards the camera bump - I'll be sure to do the same when I take my waist measurement from my ankle...

. Customers have lapped it up because we're into the eco-system and have liked the products but it shows that sloppiness or odd priorities are becoming more common at Apple.
It's an internal Apple obsession that stretches to iMacs as well - conveniently forgetting the deep stand they sit on, rendering any "thinness" redundant while sacrificing better internals for laptop quality components. It's meant I've ordered a Windows 10 PC instead sadly, I wanted an iMac but for the rendering work I do it's just not up to scratch.
I just feel that Apple have peaked I guess, it concerns me that we're starting to see a trend of sloppiness and disregard for what customers actually want.