6 digit years seem like a solution to a problem that will never be for the sake of looking forward thinking. There's absolutely no way current technology or social norms will last 8000 years.
Let's say you run a climate calculation for long enough for example. Now you could just say "fuck dates" if they error — but wouldn't it be kinda nice if they didn't?
"Hey, this guy had set his reminder to today. I wonder what he'd think if he knew we actually saw this 56,000 years later"
"Well, let's regenerate him and ask"
Part 2 of the standard gives examples of years with 10 digits.
(I can definitely see cases where 6 digit years would be useful, tho)