I'm wondering why this is case. It would be very helpful to be able to tint black and change that per skin. Is this something that could be fixed/changed in a future update?
Just to clarify, this would be helpful in regards to spritesheet optimization. Sure, you can recolor the artwork and use multiple sprites, but it would be great to reduce all the sprites to one, tintable asset. Without tint black, it's impossible to get the colors right using one sprite.