Note that the public release or ROM is designed as a basis for your own work: you will want to make it your own by customizing the areas and the code for your own tastes. You will want to add your own spells, skills commands and features.
If you want to be violently ill, check out http://members.xoom.com/anti_med/ and see the evil story of "Medthievia" (the polite name for Medievia), a Merc-based MUD (like ROM) where the Imp shamelessly violates the license terms. Michael Krause, the implementor of Medievia, is also CTO and a bunch of other things for an outfit called InvestmentDiscovery.com. I wonder if they know that Michael has signed a statement, "under penalty of perjury" that posting Diku-derived code (complete with comments from the great Furey's name) is a violation of copyright.
Don't be a doody-head like Mr. Krause: -follow- the licenses. It's not just the moral and ethical thing to do, it's the law.