In the end it all comes down to whether content creators are okay with their themed material being used the same way on another server. Yeah, it would make anyone mad, if their motto isn't to share easily accessible contents and they're a full fledged tripfag beyond reason. Of course they'll be angry, they want to have a one-of-a-kind server with a specified theme created by none other than their own developers. That's what makes variety, in it that no server will ever be 100% the same, despite how much stolen content had been extracted from one server to another. But aren't all private server owners guilty of this crime? Haven't we all stolen what was previously a payment model mmo? Call it the 'grey area' if you will, but lets not forget that forging a private server of your own isn't exactly legal. It's within the realms of what RO emulators were in the past.
Saying that you would take virtual actions against RO creations taken from you by practically anyone who can get it, while running a server of your own, is like the MPAA vs Open Source, or like a lawsuit between a rapper and reality show redneck over which one of them owns the phrase, "Yuuup". It's borderline hypocrisy.