Why shouldn't I be the only one with the right to sell that image?
The course of action for "lose the rights in 20 years" isn't "ok, that's fine" but rather "ok, then I won't publish any of them and deal only in direct sales of prints from a gallery."
The real answer is why should you? Copyright is not a natural right (if it was, it wouldn't require enforcement actions on people who never interacted with the original copy). It's a privilege meant to provide an incentive for artists (the effectiveness of which is questionable, even without taking into consideration the negative side-effects).
> The course of action for "lose the rights in 20 years" isn't "ok, that's fine" but rather "ok, then I won't publish any of them and deal only in direct sales of prints from a gallery."
And that is entirely within your rights. But once your photo is disseminated into the public sphere, it's information that you no longer have control over.
The Library of Congress is just an example, I'm sure some international agreement could be made for an independent entity.
As for the Berne Convention or TRIPS, I wasn't just talking about the US. The international copyright laws should also be reformed.