Because virtually no one will be able to qualify to pass that law. We don't make laws for 200 mph speed limits, even thought there is a cadre of people who can and do drive at those speeds. Legally fictitious people. Let's say the average person is 35 and will be 36 by the times copyrights go into effect on New Year's day of the next year. We can't rely on laws that put all the power in the hands of a set of corporations, or rely on people who haven't aren't born yet to think enough of what we are reading to today to publish it for our children's children's children over 100 years later than when we first saw it.
Publication needs continuity. .
Some people say the amount of information is doubling every 14 years or so, others say it is around every 10 years, and newer estimations range all the way to a doubling every 2 years. When copyright was first invented, it was a total monopoly for the one single house that controlled it, and the total world's population at the time was somewhere around half a billion. And often this work is small enough to fit in your pocket. The same is true for recording some records or acting in movie productions, or producing them. The world's best athletes have to compete season after season, year after year, Olympics after Olympics.