They provide ideological cover and propaganda support fire. Every time there is anything controversial about music copyright, artists’ associations roll out spokespersons to justify the moves, because it plays well with their members.
Not more than they are harmed by the looting of the public domain that media conglomerates are engaging in. Having a small public domain hurts everyone who can't afford a legal team to research and litigate for them. When you weigh the heavy costs against the slight benefits, it's a net loss.
I know a few artists that suffered quite a lot of theft primarily in art assets and concept work including their work being used as concept art for commercial projects and textures and 3D models even shipping in with some.
Even in such cases like bargain bin games which were made by a Russian and Chinese studios and were published in Europe by fairly large publishers and used stolen assets they had little to no legal recourse the Publisher didn’t care, the artists don’t have the money to fight a legal battle and even if they do win at best they’ll barely cover their legal fees if they even turn a profit and the game devs would just patch those assets out if they would even exist by the time the case is settled.
From their point of view it’s not that the public domain is too small but that the current copyright laws are too lax and can only be used by those with large legal teams on retainers.
What you are talking about was already covered by the old copyright system. The new copyright system only adds protection against uploading the stolen work on an asset store.
Also the big publishers can now just submit your work to the copyright collectives and you will receive rakedowns on assets you own. Good luck proving that though.
Just wanted to chime in that I agree with you. I had some artist friends who were pro strong copyright, but personally I don’t think they realize the vast groves of information everyone on earth is being deprived of for this scheme. We absolutely need to find ways to compensate artists but I think the cost of copyright is far too great.