Even if the number of inventions went down, there are always upsides. Less time and money wasted on litigation and better products for consumers.

But things like complex circuits would see drastic reduction in R&D if competitors could just make a copy.

You'd save money on litigation, but it's not that much considering the size of the industries at play.

And you'd probably see worse products after the short term.

If you took more than a cursory glance at the pharmaceutical industry, you'd see this oft-repeated claim is bullshit. Pharmaceutical companies spend billions on marketing (as well as lobbying politicians and doctors) and attempting to re-patent old drugs as their patents expire. They spend very little on blue sky, highly innovative drug development. That is mainly the province of publicly funded research labs and universities.

The one thing pharmaceutical companies actually do is cover the high cost of clinical trials. I see no reason we couldn't replace that with a publicly funded mechanism, do you?

It effects all industries that have R&D, those are just good examples.

Forget about tv, high budget video games, movies, etc. That stuff takes serious investment to make.

This is a ridiculous claim. DIY and free music culture has made a lot of unique stuff. Have you heard of the band "Bomb the Music Industry!"? That was their whole thing. Musicians already copy each other in general, but the problem would not get worse.