I guess I didn’t properly answer why I don’t upgrade. The simple answer is if it isn’t broke, why attempt to “fix” anything. I deal with enough broken tech in my everyday job, I don’t need to challenge myself more if there isn’t a real benefit. That’s all.
OK, but your missing about 12 updates and 12 security updates I think and a lot of things change in a year or so from 6.6 to 7.8 
I am not even sure you received the update to Android 16 that came when 7 was released.
I think you would be surprised at how much you are missing as I just searched iode 6 read the features and iode 7 and read the features and there were some nice changes.