So far as making money goes, the relevant parties are:
- The original creator, and their agents, who would like to retain intellectual property rights for as long as possible in order to profit from the work, and
- Creators of derivative works, who would like to gain access to the intellectual property rights as soon as possible in order to profit from the work.
These are of course mutually incompatible. There's clearly
some reasonable point at which works pass into the public domain, otherwise we'd be paying royalties to the heirs of Homer for the Iliad. At the same time, whilst some creators might create things without any certainty of receiving income, no sensible publisher house is going to print something that'll be copied hither and yon with no hope of recourse.
From a policymaker's perspective, the relevant question is - at what point does the social value from permitting the creation of derivative works exceed the social value from incentivising the creation of novel works? And how do you perceive 'social value' anyway? One way - probably not good, but at least measurable - would be tax income. Another would be the net rate of creation of works. There are probably others, and I doubt even most policymakers are really thinking in those terms.
From my perspective, as a mere consumer (though with aspirations!), I don't believe that corporate authors holding indefinite copyright is desirable. But it probably is reasonable for authors to expect to benefit from their work, if not for their entire lifetime, then for a substantial portion thereof. That leads me to the conclusion that copyright ought to be valid for a reasonably long period after creation or publication, in the vein of current US copyright law. Precise durations are, of course, wholly arguable.