Author A writes something incredibly popular and dies the moment he wrote the last word. His children end up in the poor house because they don't get any royalties from sales.
Author B writes something incredibly popular at the age of 15 and is still living large off his royalties at the ripe old age of 100.
If you just set it to, say, 20 years and it's done (or IMO better would be an exponentially increasing fee for renewal, $1 for the first year, $2 for the second, $4 for the third, etc.) then it seems to be more predictable and cleaner.
Considering two extreme cases:
Author A writes something incredibly popular and dies the moment he wrote the last word. His children end up in the poor house because they don't get any royalties from sales.
Author B writes something incredibly popular at the age of 15 and is still living large off his royalties at the ripe old age of 100.
If you just set it to, say, 20 years and it's done (or IMO better would be an exponentially increasing fee for renewal, $1 for the first year, $2 for the second, $4 for the third, etc.) then it seems to be more predictable and cleaner.