Because 15.5 still has bugs affecting my 13 mini. Also, battery life has regressed from 15.4.1. Still on 14.8.1 with my 3 XRs.Why holding out?
With the length of time it is taking Apple to release 15.5.1, I am hoping it is because they are crushing enough of these annoyances. If nothing is blaring when I update my 13 mini, the rest of my devices will finally get caught up to iOS 15.
Also reading about all the new gimmicks iOS 16 will have, next summer seems to be a reasonable time wait to have them working as they should. Maybe I will update to iOS 16 sooner, but I refuse to be part of Apple’s bug team for them to get it right.