Don't assume that those who are against all copyright hold this position in isolation from other politics. Some of us think that much of the economy needs to change in significant ways, and copyright would be just one aspect of that.

And there are changes that aren't even all that radical, that are enough to make a counterpoint here. For example, with a sufficiently generous UBI, a lot more people would be able to pursue arts for the sake of arts. One could reasonably argue that removing the profit motive would not only not break such an arrangement, but improve the quality of the output.