Quote from FaithlessLootingYou wouldn't use a white Argothian Enchantress in lieu of a green one, you'd use it instead of GSZ.
Again, the White mana required van be really annoying when the core of the deck is Green because of Wild Growth and Utopia Sprawl. Casting an Enchantress ASAP is a priority, and occasionally White mana isn't available. Yeah, you can add more Savannahs (and maybe Horizon Canopy), but then you blunt one of the great strengths of Enchantress; the ability to laugh at non-basic hate.
It's definitely possible to print a 1WW 0/1 enchantress with hexproof.
Certainly, but it would see almost zero Legacy play, and shouldn't be driving speculation on Serra's Sanctum. That would be, if anything, more of a niche Modern card. Might even be too slow for the format, and Liliana is a thing in Modern as well.