Sure! Yes! I agree! 100 years is way too long. 20 years is much more reasonable. But the comment that I was responding to (and many others in this thread) are advocating for the complete removal of copyright, and that's what I'm responding to.
I was not advocating for the immediate complete removal; I acknowledged that this may be too disruptive.
I was simply reminding people what direction we should go in, and what the stakes are. Reducing copyright terms is a great solution, and yes something between 2 and 12 years is probably the right number to aim for as a first step. I agree with the above commenter that 20 is far too long, because 20-year-old material is slipping into irrelevance in many cases.
It's also good to remember that the only reason we have copyright (in the US, where "moral rights" are not a thing) is to stimulate the creation of more work. So we need to think about what configuration of copyright law actually stimulates more work, and we need to be willing to experiment.
For the life of a human, yes, for the life of a corporation, it's long but not too long. Specially for corporations such as Disney which are sure to last for quite a while.
Not saying this is a justificable position. I'm actually in favour of drastically reducing copyright (I believe 7 to 15 years might be a sweetspot). But a lot of laws are not made for regular human people any longer.