You kinda failed to answer the question, "Then explain how charm works?" Again, there are splash arts like -
HeartSeeker Vayne - Holding a love letter from Mundo and with Mundo shot with a bolt/arrow in the background.
Battle Bunny Riven - What is believed to be Zac blushing at Riven.
Skins aren't always followed by lore or what. There are skins the bend the lore in different ways like what if they are from a different place or was turned evil/good instead. There is nothing wrong with it. All it does is to add more content and people can buy the skins if they like them. If not, then you shouldn't be the guy that says no to new content.