If the mask does not only give you the visuals but also racial traits and skills, the mask is pretty op. Playing every other race in competitive play will just put you at a serious disadvantage. Undeads already have heavy advantage with 'playing undead' and immunity to death fog and the mask negates not only their main weakness (getting avoided by NPC), but also grants you the benefits from every other race, as it seems. So you can combine strengths of undead with strengths of elfs.

Because honestly the other races are pretty weak anyway, if they did not change that fact with a huge overhaul for the release.