Because copyright laws (in the US at least) are (supposed to) provide to creators a limited time monopoly on their work in order to "To promote the Progress of Science and useful Arts".

Getting the right to squat on a piece of art that you claimed copyright over but not doing anything with is counter to that whole purpose of providing copyright in the first place.

> Secondly, that puts an unfair burden on creators. If I do a run of of my book, and it sells out, I don't think it becomes open season on duplicating it digitally, and I shouldn't have to always carry excess inventory just in case it's a hit.

This is a strawman interpretation. There is a lot of room between "I ran out of stock today" and "this game hasn't been on sale for 3 decades".