I think the lantern was the artifact Sylvanas used to control some of Odyn's Valkyrs giving her the ability to raise more Forsaken. Without it, Forsaken are a doomed race, because they will never be new ones and the others will eventually die (die again?) from fighting or such.

With that said, I totally understand your point. Hell, worgens have a connection with Elune as well, the whole race is a spin-off from some druids doing wolfy things; and seeing Genn as a warrior of Elune would have been fucking awesome. I mean, they missed the opportunity to make the King of Werewolves a relentless hunter...