There are unfortunately showstoppers to remaining on the original iOS version. Safari on iOS 15 shows most websites as “unsafe” for me, requiring two or three extra taps on each page refresh, I believe because the certificate root stores are outdated. Also some banking apps I use require iOS 16 or newer.Yeah, but it is such a horrible consequence of iOS updates that I’d make sure it is as well-optimised as possible for the oldest supported device.
It is absolutely obvious and annoying when it happens. I’ll go as far as to say that I don’t know how people tolerate it.
I always run original iOS versions and never update, but I’m so annoyed by it when I use an older, updated device.