Your latter point applies. Now. Copyright doesn't factor into the planned obsolescence textbook industry to avoid used copies. Interestingly, that imitatates the game industries attempts to circumvent used games sales.
That highlights a deeper problem, there is a psychological divide between the IP and the plastic discs or dead tree they are placed upon. The authors wouldn't care if you shared their book if whenever anyone but you (the purchaser of a license to the work) saw blank pages, but you can redistribute their information via traditional economic goods exchange and they don't like that because in modern times copyright lets them lockdown distribution (for most people) all the time.
To answer your first question, here is the opposite perspective:
Throwing away copyright, why not let people freely exchange the information they have? You answer with "the creator needs incentives to create and a means to eat" but you could just switch to the patreon model - have per-work payments by your consumers directly. Then release your work, and let anyone else redistribute as if it were public domain.
Because inherently copyright says you don't have rights to do what you want with the things you possess, if the thing is information, be it encoded in neurons in your brain, etched upon dead tree, engraved in a plastic platter, or stored in a large transistor grid. The codification that some intangible concept that can transcend medium is not yours to do what you want with - for every single copyrighted IP concept or work - is a limiter on the possessor for the benefit of the rights holder.
It is also important to differentiate the rights holder from the creator - since the vast majority of IP created today is not under the license of its creator but under the license of their employer. Which is why the life of author + 70 mess comes in, because huge corporations want never ending money for some work they spent finite time and effort making.
I'm a copyright abolitionist - I think the world would all around be a much better place if content creators pursued their own fans to pay their bills so they can create more. Given a sufficiently good earpiece to get the word out about new creators, and an easy way to discover them, it would be effectively a meritocracy of creative talent.
I'm not advocating theft - and it is important to remember what copyright means - this isn't taking something from a content creator and passing it around nonchalantly. It is that when a content creator voluntarily gives you a copy of their work, that you can do whatever you want with it, including redistribute it yourself. If you break into someones house and steal their work in progress book they never finished, that is robbery. You are stealing their physical property containing their IP, and since that wasn't a voluntary exchange of the initial information that is theft.