High Templar Weapon Effect only working on "Undead" literally?

Dear GGG-Team,

I just bought the High Templar Weapon Effect and was expecting it to be just "cool wording" to only work on Undead monsters. But it literally does. The effect is awesome and it's amazing to have some kind of on-death effect without explosions in the game. Loved the Ghostflame Treasure Hunter effect for the same reason and expected this High Templar Weapon Effect to be the same.
So are people on YouTube commenting under the video. I think everyone expects it to work with every monster, because why would it only work with 10% or so?

I would kindly ask you to consider making this effect work on every monster type. The MTX being in the highest tier (90$) and only working on such a small number of enemies is unexpected.

Thank you for reading.

//edit: It also seems to only work with on-hit-death. Please reconsider to make it into an on-death effect like the Treasure Hunter weapon effects. It was such a cool addition to the game.