story
"Economic analysis has come up short of providing either theoretical or empirical grounds for assessing the overall effect of intellectual property law on economic welfare."
And that is echoed in various other economic comment in later years. So there is an uncomfortable lack of research.
Now, the main purpose of copyright is to get the best trade-off in production level and access to goods. So given both that model and the lack of evidence, to say an increase in availability of goods, with a still strong level of production, is a good thing, seems very reasonable, does it not?
> losing 'potential income'
What does that even mean? Really, what? If people buy more coffee machines and make coffee at home, perhaps coffee-shop owners are going to say they are losing 'potential income'. Oh no! we had better ban the use of coffee-making machines!
The law is not there to ensure certain businesses make as much money as they think they should. (Well, sadly it currently is, but it ought not to be.)