My problem with selfies isn't really their inclusion in World of Warcraft (or any game), more the cultural impact they're having in real life. I find it extraordinarily strange that people are entertained by photographing themselves in the most mundane of locales, and then posting them on social media assuming that people will care. I was at a gig recently, and couldn't believe the number of people who were busy taking pictures of themselves and posting them to Facebook... Rather than enjoying the performance on stage.
It just baffles me.
So, in my view, it's perhaps not a huge surprise to see such a feature appear in an expansion as light on meaningful content as Warlords of Draenor. With no actual content to be had, a weekend project finds its way into the game so that people can take pictures of themselves in the world... Rather than actually playing meaningful content within the game. When Twitter integration is lumped together with this, in one of the most threadbare "content" patches in the game's decade stretch, it honestly seemed like I'd just taken up residence in the Twilight Zone.
But worst feature?
Nah. I'm not sure you can call anything the worst feature - if someone doesn't use something, or doesn't even know it's there, it's hard to argue that it's "bad". It's just ignored.
If even only a handful of people have gotten some fun out of the S.E.L.F.I.E camera, then it's a success for that handful; and that's good enough for me.