In the same paper abstracts, they also mention how bitterness itself suppresses sweetness, so by suppressing bitterness with salt, you also make any sweet notes in the coffee stand out better. This might be another reason why salt makes it more palatable.
My poor memory is telling me the heat is used to make the bits easier to flip, so you can use a weaker magnetic field that only affects a smaller area, allowing you to pack in bits more closely. It shouldn’t have the same problem as SMR.