I think technically this is a designation applied to a MU* in which a wizards not sporting broadswords and platemail are not automatically beat down. Many (most?) MU*s do not encourage or require a player to actually ACT anything like their character and in many cases, it's quite stupid or considered bad form to actually role-play. A roleplayer friendly MU* is one that does not penalize you for acting like your character would act. Compare to roleplay required.