My reason for not updating is because I use iTunes 10.6.3, which has USB sync for contacts & calendars, and even PowerPC. I was using iOS 5.1.1 for a long time, until a broken Cydia package forced me to restore, and then I had to downgrade using OdysseusOTA.
Software rot is a daily problem. LINE is discontinuing support this week. It's like the software is forcing me to upgrade my hardware.
The day will come when my phone will break. Unless Apple dramatically changes course and brings back their ecosystem, that will probably be the day when I leave iOS altogether.