I don't buy this. Google any popular game out there and you'll find a literal shit ton of "copyrighted/trademarked" skins out there freely available. some of them have been around for decades. YouTube is polluted with videos of people playing games using custom skins. Where's the cease and desists from Disney? Nowhere. They go after people trying to profit off selling stuff.
And who exactly are you to define what is or isn't "creative"? Go to a comic con sometime and take a look and the amount of time, effort, money and blood sweat tears that some of the people put into making cosplay costumes of their favorite characters. They're doing it because they love these characters, not to rip someone off. Marvel, Disney and WB aren't at the door handing anyone C&D orders and telling them to get changed. How is that any different?
This rule was put in place here to appease the few who lost their shit over other people making homages for "not being creative enough". however, it's their servers so it's up to them what to do, so we have to live with their decision since we don't have the skin in the game they do. chances are greater they do something to piss off NCSoft and that gets the game shut down than someone making a Superman homage.