i feel like this is the sort of thing that wizards R&D would probably not care about ultimately. cards that showcase design principles in clever/subtle ways are only really appreciated by people who are both familiar with those design principles and interested in design itself, which probably describes a mostly negligible amount of players.
This is literally the set for that. That is the whole premise of Modern Horizons sets. They are concepted as Time Spiral sets, sets that are about being clever and quirky in ways that the usual premier sets cannot. Modern Horizons 1 is where
Smiting Helix and
Twisted Reflection are, which are cards whose whole point is just to point out interesting things about the color wheel. MH2 even pulls a Planar Chaos and colorshifts
Yawgmoth's Will into
Gaea's Will as part of a cycle that is about suspending classic OP cards.
Except
Damnation already exists (albeit originally from Planar Chaos), and black already gets conditional sweepers like
Toxic Deluge,
Languish,
Consume the Meek, so it wouldnt be out of the question for a black
Day of Judgment to exist.
Having said that, this might be a good question to bring up to MaRo from a design perspective as then there would be an official answer
The point is not "Black cannot get Wrath of God"; it's that "White can get Wrath of God but not Murder."
This exact card has been posted a million times in various custom card forums. Like Libe said, "Every YMtC person has thought of this card, so it's nice to finally see it printed." I am honestly confused why this card is confusing.