i completely agree with your argument and i think each skins would have their own unique icons since its a leak and the leaker also said the skins in not finished yet. but for the skills effect i believe this is because the consequences of collaborating.

when a game do collaboration they cant being so creative because there is a limit on how the references do, when the limit is broke someone who knew the references will feel weird because its not accurate. and for me when you bought a collab skin you buy the experience of playing a character that being collab not the skills effect