Well, if you have a big company where the main asset is some copyrighted material and the creator suddenly dies, that company might suddenly lose a lot of revenue possibly affecting the life of a large number of people. (Of course, you might say, that's business and it just means that another large number of people now have a new business opportunity.)

I think the current life+70 years is wrong, but I think the expiry should be predictable some time in advance. Like X years from the time of creation.