The Switch is a portable device, so this "slow media" would have to be some form of solid state memory. And unfortunately, cheap flash memory tends to also have a short self life. That doesn't exactly help with preservation!

All else being equal, I'm happy Nintendo went with the more expensive media, even if it means some smaller titles likely won't be available physically. (In my eyes, a key card does not count as a physical release.)

I'm mostly just happy the key cards are clearly labeled so I can avoid buying them...