What do you mean "trash"? Any N64 emulator can upscale games just like Duckstation. And they don't need perspective correction because that's already there, natively.
A more reasonable explanation is that a lot of PSX games have already been ported on PC. All Resident Evil games, WipEout, Final Fantasy 7, Metal Gear Solid, etc, all have official PC ports. Most of these ports already have very good mods. But N64 exclusives only get official releases on Nintendo consoles. And sure, you can still emulate them on PC but modding them this way is harder.
besides what others have said, the main reason is the Mario 64 Decomp, that project made a lot of tools and documentation of how to decomp a N64 game, making it easier to decomp other N64 games. Take in mind that the Mario 64 decomp project took years, with a lot of people working on it, it was basically a professional decompilation project.