I think the reason for this is that Apple only gave importance to design that year. iPhone 6 came with a brand new design. I'm sure that design takes up most of the iPhone 6's R&D. As a matter of fact, the guys forgot to take care of the hardware part of the iPhone 6. It had a lot of shortcomings like 1GB of RAM, A8 SoC, eMMC storage. The A8 promised almost nothing in terms of performance compared to its predecessor, the A7.The 6 Plus was the worst iPhone I ever had. 1gb ram and 64 bit never should have happened. Crashy, constantly refreshing apps, played a podcast-paused-looked at Safari-pressed play again-music started playing as the podcast app was flushed. Terrible.
Although it never bent and I used it caseless like all my iPhones.
My first iPhone, the 3G, was pretty ropey in hindsight but I LOVED it at the time so it doesn’t qualify.
Yes, the number of transistors has increased, nanometers have shrunk, but we had almost the same SoC as the A7. It would not be wrong to say that the iPhone 6 is an oval iPhone 5S with a redesigned and enlarged case. The withdrawal of its support with the 5S at the same time proves this. The iPhone 6 is the poorest device in the history of the iPhone in terms of hardware.