Maybe I'm just in the minority here, but I really don't see much reason to go back to PS1/2 games. Not to say they can't be good, and I'm CERTAINLY not a graphics whore (the games I play the most lately outside of Elden Ring are pixel platformers like Terraria, The Messenger, Shovel Knight, and Kaze and the Wild Masks...you know, stuff like that), but like, N64, PS1, and PS2 games have not held up. Every time I go back to them I think, "Man, these games are a lot better in my memory than they actually are." SNES games held up. Gamecube games held up. NES games mostly hold up. Genesis games mostly hold up. A lot of old games hold up, but a lot of games from the 5th and 6th generation of consoles (The PS1 and PS2 era, alongside N64, Gamecube, and original Xbox) really haven't held up well at all. They just feel like inferior, clunky versions of better games.
I tend to agree that my own interest in legacy titles is particularly low. The only stuff I'm interested in is what I played before (and LoD lol). That said, the chance that trophies are added to other games now has got my interest: I'm willing to look outside at other games I missed.
But I think this will fare better than you believe. I agree the metrics have showed that BC is not as big a feature as people make it out to be, but I feel that the likes of GamePass has presented this idea of an evolving library that combines both old and new. And this has inevitably increased the viability of legacy titles.
I hope Sony is able to go all out. I'm definitely more interested in this than I would've been a couple of years ago.