Technically, the Constitution says the purpose of granting copyright protection is “To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries.” (Art. I, Sec 8(8)) Allowing people to recover their investment is one way to do that, but in theory return-on-investment provisions should be held up to the “promote progress” standard. I think both you and Pollock argue convincingly that current copyright law isn’t very well-suited to that purpose.