Who knows what the real legal rules are surrounding this, but my own personal principal is that if it not available anywhere else commercially apart from used/secondhand copies, then piracy in any form is acceptable, as long as you at some point in your life have spent money on it. The movie and TV industry does a fairly well job of keeping their content available in some way shape or form, at least better than the games industry IMO, so there is most likely some way for you to find a movie or show to watch in a way that is legal. Streaming, buying/renting digitally, or buying physical copies, these are usually available for nearly any show or movie made, at least in NA.
As for games, there becomes a time where a game is flat out not profitable for the company whatsoever. The game is old, outdated, surpassed by better games, didn't sell well and generally forgotten, licenses expire, there are so many reasons for a game to essentially drop off the face of the earth. If the company that owned the rights to a particular game wanted to for any reason, they would sell it in some form officially. Old games don't even need to be remastered or enhanced, they can just exist in the form they released in, just made to be played on modern systems which can be incredibly easy, and that is all it takes. As far as I understand it, it doesn't cost the company anything to keep their games on digital store fronts, maybe a small fee but typically negligible for the company.
I could very well be oversimplifying this entire situation, casting a very general blanket over the causes and situations for a game not being commercially available, but I think for the most part there shouldn't be any major reason besides licensing and contracts expiring for a game to not be available to purchase in some form. Companies should try harder to just make these games available in some way. As I said before, it does not have to be some remastered edition that potentially costs more to make than the original version, just look at GOG. They have implemented testing and software to ensure old games run great on modern systems, and besides that they are not enhancing, remastering, or altering the game in any way and the players love that. We want to play the game in the way that we remember it.
So to conclude, I think companies need to have more ways to make their games available. If I want to play something and I no longer have my original copy, then I will try to find it online. If I can't find it available to purchase officially anywhere besides used copies, and I see it on myabandonware.com or the Internet Archive, then I will download it there. I no longer use real pirating sites, so those two sites are about the furthest I go with "pirating". Usually I can find whatever it is i'm looking for on there.