The difference is that hardware failure is on the user's end. The games still exist and are playable unless there are no more working SNES or PS2 out there.
That's just not true. Every cartridge battery will eventually die. Every CD and DVD has a limited life span. All optical disc lasers will eventually die. Physical media is not future proof by any stretch of the imagination, and at some point in the not too distant future a majority of old games and consoles will no longer function through no fault of any user.
True, but every SNES and PS2 game has been dumped/ripped and they exist as perfect digital copies in so many different places that they're now preserved forever. The lifespan of the original media is no longer relevant.
Obviously this sort of thing gets much more complicated with digital-only games and huge day one patches, but even there, people are figuring out how to dump updates from digital stores and preserve them.