which is too long, and also too short - what about authors who wrote finished their book on their deathbed? Then their rights are shorter than someone young - an unfair discrimination.
That's why age should be irrelevant. Copyright is useful, and should be granted. However, current copyright grants last far too long - age plus some years beyond. Not to mention corporations lobbying to increase the length right as some copyrights for some works are about to enter public domain.
Therefore, copyright should be granted for a single period and end - like patents. 20 years seems to be a good middle ground, but i could hear arguments for slightly longer or shorter.
I suggest to rather look at it under the angle whether estates should be able to inherit author’s identity (or some of it), to continue the will.