I'll give it a go:
It's a bit like a startup. That is: creating the thing isn't the only part - getting people to want it, i.e., finding a market for your product, is intrinsical.
Case in point: Van Gogh. He only became greatly appreciated after his death.
What does that mean for copyright? In this line of reasoning, copyright during life of the creator is reasonable. A work may become a cultural touchstone for ever (Michelangelo's Sistine Chapel, Bach/Mozart/Beethoven), for one or two generations (Elvis Presley/Cliff Richards[1]), or maybe it becomes simply widely known without being considered an indispensable part of culture (Venga Boys - Boom Boom Boom). During life of the creator, the creator's efforts should be protected and she/he should be allowed time to get her/his creation ingrained in general consciousness. Post-life, the heirs could be allowed some time to reap what was sown - e.g. 10 years, extendible once for 10 years for payment.
As the OP, I'm not saying this is my view on copyright. I am wondering why society should think it owns something I created. "Because others benefit" is insufficient in my opinion: if you're posting on HN, you're in the wealthy half of the world population. Others would benefit if society took half of what you own and distributed its value to those significantly less well off.
I'm in favour of the concept of ownership myself, but I don't see why creative works should be exempt from that.
[1] at one point in time, there was an Elvis vs. Cliff vibe. Possibly strength depending on where you lived (more apparent for UK/EU folks?).