Optical size variants (the size at which the text appears in your field of view, and its size relative to other type in a layout) are different from DPI variants or paper coarseness variants, though.
Paper coarseness variants will generally be designed around the physics of ink, to trap it in the junctions of small letterforms and prevent ink bleeding. Optical sizes tend to be more about the relationship between headline and body, with things like tighter standard kerning, taller x-heights, and so on. A DPI variant should only concern itself with aliasing, and aliasing is a render-time issue. You can design a typeface to counter this from the foundry side, but a more sustainable solution would be to counter it from the software side.
You're right, they're different. I was just pointing out examples where foundaries produce variations of the same typeface to account for differences between media.
Anyway, as long as such differences exist, I don't think we'll be able to convince type designers to disregard them. They want their fonts to look perfect now, they're not going to wait for smartphone manufacturers to catch up, and they already have the skills and tools to produce subtle variations of their typefaces.
A truly sustainable solution would be for every reading device to have 300ppi+ screens so that it doesn't really matter how you shade the last subpixel. Until we have that, leaving optimization to perfectionist type designers seems to me like a better stopgap measure than trying to standardize on one or another antialiasing algorithm across vastly different platforms.
Different vendors like Microsoft and Apple use antialiasing algorithms that are not only technically different but also based on different UI paradigms. (MS emphasizes crispness whereas Apple emphasizes preserving shapes.) Neither is obviously superior to the other, and the choice is to some extent a matter of taste. So it should be the designer's prerogative to decide whether to follow either paradigm or to disregard both and enforce his own aesthetic tastes.
Paper coarseness variants will generally be designed around the physics of ink, to trap it in the junctions of small letterforms and prevent ink bleeding. Optical sizes tend to be more about the relationship between headline and body, with things like tighter standard kerning, taller x-heights, and so on. A DPI variant should only concern itself with aliasing, and aliasing is a render-time issue. You can design a typeface to counter this from the foundry side, but a more sustainable solution would be to counter it from the software side.